Interesting question indeed, and there's more than a few possibilities to select from!
Firstly, from Bhikkhu Bodhi's introduction to the Samyutta Nikaya (on the reasons he translated the term as he did...)
In MLDB (Middle Length Discourses of the Buddha) I had changed Ven Nanamoli's expermental rendering of sankhara as 'determinations' back to his earlier choice, 'formations'. Aware that this word has its own drawbacks, in preparing this translation I had experimented with several alternatives. Thos most attractive of these were 'constructions', but in the end I felt that this term too often led to obscurity. Hence, like the land-finding crow which always returns to the shop when land is not close by (see Vism 657; Ppn 21:65), I had to fall back on 'formations', which is colourless enough to take on the meaning being imparted by the context. Sometimes I prefixed this with the adjective 'volitional' to bring out the meaning more clearly.
Sankhara is derived from the prefix sam (=con), "together", and the verb karoti, "to make". The noun straddles both sides of the active-passive divide. Thus sankharas are both things which put together, construct, and compound other things, and the things that are put together, constructed, and compounded.
In Samyutta Nikaya (SN) the word occurs in five major doctrinal contexts:
As the second factor in the formula for depenedent origination, sankharas are the kammically active volitions responsible, in conjunction with ignorance and craving, for generating rebirth and sustaining the forward movement of samsara from one life to the next. Sankhara is synonymous with kamma, to which it is etymologically related, both being derived from karoti. These sankharas are distinguished as threefold by their channel of expression, as bodily, verbal, and mental (II 4, 8-10, etc); they are also divided by ethical quality into the meritorious, demeritorious and imperturbable (II 82, 9-13). To convey the relevent sense of sankhara I have rendered the term 'volitional formations." The word might also have been translated "activities", which makes explicit the connection with kamma, but this rendering would sever the connection with sankhara in contexts other than dependent origination, which it seems desirable to preserve.
(2) As the fourth of the five aggregates, sankhara is defined as the six classes of volitions (cha cetanakaya, III 60, 25-28), that is, volition regarding the six types of sense objects. Hence again I render it volitional formations. But the sankharakhanda has a wider compass than the sankhara of dependent origination series, comprising all instances of volition and not only those that are kammically active. In the Abhidhamma Pitaka and the commentaries, the sankharakhanda further serves as an umbrella category for classifying all mental concomittants of consciousness apart from feeling and perception. It thus includes all wholesome, unwholesome, and variable mental factors mentioned but not formally classified among the aggregates in the Sutta Pitaka
(3) In the widest sense, sankhara comprises all conditioned things, everything arisen from a combination of conditions. In this sense all five aggregates, not just the fourth, are sankharas (see III 132, 22-27), as are all external objects and situations (II 191, 11-17). The term here is taken to be of passive derivation - denoting what is conditioned, constructed, compounded - hence I render it simply as 'formations', without the qualifying adjective. The notion of sankhara serves as the cornerstone of a philosophical vision which sees the entire universe as constituted of conditioned phenomena. What is particularly emphasised about sankharas in this sense is their impermanence. Recognition of their impermanence brings insight into the unreliable nature of all mundane felicity and inspires a sense of urgency directed towards liberation from samsara (see 150:20; 22:96)
(4) A triad of sankharas is mentioned in connection with the attainment of the cessation of perception and feeling: the bodily formation, the verbal formation, and the mental formation (IV 293, 7-28). The first is in-and-out breathing (because breath is bound up with the body); the second, thought and examination (because by thinking one formulates the ideas one expresses by speech); the third, perception and feeling (because these things are bound up with mind). Two of these terms - the bodily formation and the mental formation - are also included in the expanded instructions on minfulness of breathing (V 311, 21-22; 312,4-5).
(5) The expression padhanasankhara occurs in the formula for the four iddhipadas, the bases of spiritual power. The text explains it as the four right kinds of striving (V 268, 8-19). I render it 'volitional formations of striving'. Though strictly speaking, the expression signifies energy (viriya) and not volition (cetana), the qualifier shows that these formations occur in an active rather than passive mode.
Apart from these main contexts, the word sankhara occurs in several compounds – ayusankhara (II 266, 19; V 262, 22-23) jivitasankhara (V 152, 29-153,2) bhavasankhara (V 263, 2) – which can be understood as different aspects of the life force.
The past participle connected with sankhara is sankhata, which I translate as ‘conditioned’. Unfortunately I could not render the two Pali words into English in a way that preserves the vital connection between them: ‘formed’ is too specific for sankhata[i], and ‘conditions’ too wide for [i]sankhara (and it also encroaches on the domain of paccaya). If ‘constructions’ had been used for sankhara, sankhata would become ‘constructed’, which preserves the connection, though at the cost of too stilted a translation. Regrettably, owing to the use of different English words for the pair, a critically important dimension of meaning in the suttas is lost to view. In the Pali, we can clearly see the connection: the sankharas, the active constructive forces instigated by volition, create and shape conditioned reality, especially the conditioned factors classified into the five aggregates and the six internal sense bases, and this conditioned reality itself consists of sankharas in the passive sense, called in the commentaries sankhata-sankhara.
Further, it is not only this connection that is lost to view, but also the connection to Nibbana. For Nibbana is the asankhata, the unconditioned, which is called thus precisely because it is neither made up by sankharas nor itself a sankhara in either the active or passive sense. So, when the texts are taken up in the Pali we arrive at a clear picture in fine focus: the active sankharas generated by volition perpetually create passive sankharas, the sankhata dhammas or conditioned phenomena of the five aggregates (and, indirectly, of the objective world); and then, through the practice of the Buddha’s path, the practitioner arrives at the true knowledge of conditioned phenomena, which disables the generation of active sankharas, putting an end to the constructing of conditioned reality and opening the door to the Deathless, the asankhata, the unconditioned, which is Nibbana, the final liberation from impermanence and suffering.
Nyanatiloka's Buddhist Dictionary is always worth a look...http://www.buddhanet.net/budsas/ebud/bu ... dic3_s.htm
saṅkhāra: This term has, according to its context, different shades of meaning, which should be carefully distinguished.
(I) To its most frequent usages (s. foll. 1-4) the general term 'formation' may be applied, with the qualifications required by the context. This term may refer either to the act of 'forming or to the passive state of 'having been formed' or to both.
1. As the 2nd link of the formula of dependent origination, (paṭiccasamuppāda, q.v.), saṅkhāra has the active aspect, 'forming, and signifies kamma (q.v.), i.e. wholesome or unwholesome volitional activity (cetanā) of body (kāya-s.), speech (vacī-s.) or mind (citta- or mano-s.). This definition occurs, e.g. at S. XII, 2, 27. For s. in this sense, the word 'kamma-formation' has been coined by the author. In other passages, in the same context, s. is defined by reference to (a) meritorious kamma-formations (puññābhisaṅkhāra), (b) demeritorious k. (apuññabhisaṅkhāra), (c) imperturbable k. (āneñjābhisaṅkhāra), e.g. in S. XII, 51; D. 33. This threefold division covers karmic activity in all spheres of existence: the meritorious kamma-formations extend to the sensuous and the fine-material sphere, the demeritorious ones only to the sensuous sphere, and the 'imperturbable' only to the immaterial sphere.
2. The aforementioned three terms, kāya-, vacī- and citta-s. are sometimes used in quite a different sense, namely as (1) bodily function, i.e. in-and-out-breathing (e.g. M. 10), (2) verbal function, i.e. thought-conception and discursive thinking, (3) mental-function, i.e. feeling and perception (e.g. M. 44). See nirodhasamāpatti.
3. It also denotes the 4th group of existence (saṅkhārakkhandha), and includes all 'mental formations' whether they belong to 'kammically forming' consciousness or not. See khandha, Tab. II. and S. XXII, 56, 79.
4. It occurs further in the sense of anything formed (saṅkhata, q.v.) and conditioned, and includes all things whatever in the world, all phenomena of existence. This meaning applies, e.g. to the well-known passage, "All formations are impermanent... subject to suffering" (sabbe saṅkhāra aniccā ... dukkhā). In that context, however, s. is subordinate to the still wider and all-embracing term dhamma (thing); for dhamma includes also the Unformed or Unconditioned Element (asaṅkhata-dhātu), i.e. Nibbāna (e.g. in sabbe dhammā anattā, "all things are without a self").
(II) Saṅkhāra also means sometimes 'volitional effort', e.g. in the formula of the roads to power (iddhi-pāda, q.v.); in sasaṅkhāra- and asaṅkhāra-parinibbāyī (s. Anāgāmī, q.v.); and in the Abhidhamma terms asaṅkhārika- (q.v.) and sasaṅkhārika-citta, i.e. without effort = spontaneously, and with effort = prompted.
In Western literature, in English as well as in German, saṅkhāra is sometimes mistranslated by 'subconscious tendencies' or similarly (e.g Prof Beckh: "unterbewußte Bildekräfte," i.e. subconscious formative forces). This misinterpretation derives perhaps from a similar usage in non-Buddhist Sanskrit literature, and is entirely inapplicable to the connotations of the term in Pāḷi Buddhism, as listed above under I, 1-4. For instance, within the dependent origination, s. is neither subconscious nor a mere tendency, but is a fully conscious and active karmic volition. In the context of the 5 groups of existence (s. above I, 3), a very few of the factors from the group of mental formations (saṅkhārakkhandha) are also present as concomitants of subconsciousness (s. Tab. I-III), but are of course not restricted to it, nor are they mere tendencies.
As is the PTS Dictionary...http://dsal.uchicago.edu/cgi-bin/philol ... :2800.pali
Sankhāra [fr. saŋ+kṛ, not Vedic, but as saŋskāra Epic & Class. Sk. meaning "preparation" and "sacrament," also in philosophical literature "former impression, disposition, " cp. vāsanā] one of the most difficult terms in Buddhist metaphysics, in which the blending of the subjective -- objective view of the world and of happening, peculiar to the East, is so complete, that it is almost impossible for Occidental terminology to get at the root of its meaning in a translation. We can only convey an idea of its import by representing several sides of its application, without attempting to give a "word" as a def. trsln. -- An exhaustive discussion of the term is given by Franke in his Dīgha translation (pp. 307 sq., esp. 311 sq.); see also the analysis in Cpd. 273 -- 276. -- Lit. "preparation, get up"; appld: coefficient (of consciousness as well as of physical life, cp. viññāṇa), constituent, constituent potentiality; (pl.) synergies, cause -- combination, as in S iii.87; discussed, B. Psy., p. 50 sq. (cp. DhsA 156, where paraphrased in defn of sa -- sankhāra with "ussāha, payoga, upāya, paccaya -- gahaṇa"); composition, aggregate. 1. Aggregate of the conditions or essential properties for a given process or result -- e. g. (i.) the sum of the conditions or properties making up or resulting in life or existence; the essentials or "element" of anything ( -- ˚), e. g. āyusaṅkhāra, life -- element D ii.106; S ii.266; PvA 210; bhavasankhāra, jīvitasaṅkhāra, D ii.99, 107. (ii.) Essential conditions, antecedents or synergy (co -- ordinated activity), mental coefficients, requisite for act, speech, thought: kāya˚, vacī˚, citta˚, or mano˚, described respectively as "respiration," "attention and consideration," "percepts and feelings," "because these are (respectively) bound up with," or "precede" those M i.301 (cp. 56); S iv.293; Kvu 395 (cp. trsln 227); Vism 530 sq.; DhsA 8; VbhA 142 sq. -- 2. One of the five khandhas, or constitutional elements of physical life (see khandha), comprising all the citta -- sampayutta -- cetasikā dhammā -- i. e. the mental concomitants, or adjuncts which come, or tend to come, into consciousness at the uprising of a citta, or unit of cognition Dhs 1 (cp. M iii.25). As thus classified, the saṅkhāra's form the mental factor corresponding to the bodily aggregate or rūpakkhandha, and are in contrast to the three khandhas which represent a single mental function only. But just as kāya stands for both body and action, so do the concrete mental syntheses called sankhārā tend to take on the implication of synergies, of purposive intellection, connoted by the term abhisaṅkhāra, q. v. -- e. g. M iii.99, where saṅkhārā are a purposive, aspiring state of mind to induce a specific rebirth; S ii.82, where puññaŋ, opuññaŋ, āṇeñjaŋ s. abhisankharoti, is, in D iii.217 & Vbh 135, catalogued as the three classes of abhisankhāra; S ii.39, 360; A ii.157, where s. is tantamount to sañcetanā; Miln 61, where s., as khandha, is replaced by cetanā (purposive conception). Thus, too, the ss. in the Paṭiccasamuppāda formula are considered as the aggregate of mental conditions which, under the law of kamma, bring about the inception of the paṭisandhiviññāṇa, or first stirring of mental life in a newly begun individual. Lists of the psychologically, or logically distinguishable factors making up the composite saṅkhārakkhandha, with constants and variants, are given for each class of citta in Dhs 62, etc. (N.B. -- Read cetanā for vedanā, § 338.) Phassa and cetanā are the two constant factors in the s -- kkhandha. These lists may be compared with the later elaboration of the saṅkhāra -- elements given at Vism 462 sq. -- 3. sankhārā (pl.) in popular meaning. In the famous formula (and in many other connections, as e. g. sabbe sankhārā) "aniccā vata sankhārā uppādavaya -- dhammino" (D ii.157; S i.6, 158, 200; ii.193; Th 1, 1159; J i.392, cp. Vism 527), which is rendered by Mrs. Rh. D. (Brethren, p 385 e. g.) as "O, transient are our life's experiences! Their nature 'tis to rise and pass away," we have the use of s. in quite a general & popular sense of "life, physical or material life"; and sabbe sankhārā means "everything, all physical and visible life, all creation." Taken with caution the term "creation" may be applied as t.t. in the Paṭiccasamuppāda, when we regard avijjā as creating, i. e. producing by spontaneous causality the sankhāras, and sankhārā as "natura genita atque genitura" (the latter with ref. to the foll. viññāṇa). If we render it by "formations" (cp. Oldenberg's "Gestaltungen," Buddha 71920, p. 254), we imply the mental "constitutional" element as well as the physical, although the latter in customary materialistic popular philosophy is the predominant factor (cp. the discrepancies of "life eternal" and "life is extinct" in one & the same European term). None of the "links" in the Paṭicca -- samuppāda meant to the people that which it meant or was supposed to mean in the subtle and schematic philosophy (dhammā duddasā nipuṇā!) of the dogmatists. -- Thus sankhārā are in the widest sense the "world of phenomena" (cp. below ˚loka), all things which have been made up by pre -- existing causes. -- At PvA 71 we find sankhārā in lit. meaning as "things" (preparations) in defn of ye keci (bhogā) "whatever." The sabbe s. at S ii.178 (trsln "all the things of this world") denote all 5 aggregates exhausting all conditioned things; cp. Kvu 226 (trsln "things"); Mhvs iv.66 (: the material and transitory world); Dh 154 (vi -- sankhāragataŋ cittaŋ=mind divested of all material things); DhsA 304 (trsln "kamma activities," in connection avijjā -- paccaya -- s˚); Cpd. 211, n. 3. -- The defn of sankhārā at Vism 526 (as result of avijjā & cause of viññāṇa in the P. -- S.) is: sankhataŋ abhisankharontī ti sankhārā. Api ca: avijjā -- paccayā sankhārā sankhāra -- saddena āgata -- sankhārā ti duvidhā sankhārā; etc. with further def. of the 4 sankhāras. <-> 4. Var. passages for sankhāra in general: D ii. 213; iii.221 sq., M ii.223 (imassa dukkha -- nidānassa sankhāraŋ padahato sankhāra -- ppadhānā virāgo hoti); S iii.69 (ekanta -- dukkhā sankhārā); iv.216 sq. (sankhārāṇaŋ khaya -- dhammatā; id. with vaya˚, virāga˚, nirodha˚ etc.); Sn 731 (yaŋ kiñci dukkhaŋ sambhoti sabbaŋ sankhāra -- paccayā; sankhārānaŋ nirodhena n'atthi dukkhassa sambhavo); Vism 453, 462 sq. (the 51), 529 sq.; DhA iii.264, 379; VbhA 134 (4 fold), 149 (3 fold), 192 (āyūhanā); PvA 41 (bhijjana -- dhammā). <-> Of passages dealing with the sankhāras as aniccā, vayadhammā, anattā, dukkhā etc. the foll. may be mentioned: Vin i.13; S i.200; iii.24; iv.216, 259; v.56, 345; M iii.64, 108; A i.286; ii.150 sq.; iii.83, 143; iv.13, 100; It 38; Dh 277, 383; Ps i.37, 132; ii.48; 109 sq.; Nd2 444, 450; also Nd2 p. 259 (s. v. sankhārā).
-- upekkhā equanimity among "things" Vism 161, 162. -- ûpasama allayment of the constituents of life Dh 368, 381; cp. DhA iv.108. -- khandha the aggregate of (mental) coefficients D iii.233; Kvu 578; Tikp 61; DhsA 345; VbhA 20, 42. -- dukkha the evil of material life, constitutional or inherent ill VbhA 93 (in the classification of the sevenfold sukkha). -- paccayā (viññāṇaŋ) conditioned by the synergies (is vital consciousness), the second linkage in the Paṭicca -- samuppāda (q. v.) Vism 577; VbhA 152 sq. -- padhāna concentration on the sankhāras M ii.223. -- majjhattatā=˚upekkhā VbhA 283. -- loka the material world, the world of formation (or phenomena), creation, loka "per se," as contrasted to satta -- loka, the world of (morally responsible) beings, loka "per hominem" Vism 205; VbhA 456; SnA 442.