From the PTS Dictionary...
Rūpa (nt.) [cp. Vedic rūpa, connected etymologically with varpa (Grassmann). -- The nom. pl. is rūpā & rūpāni] form, figure, appearance, principle of form, etc. -- A. Definitions. According to P. expositors rūpa takes its designation fr. ruppati, e. g. "ruppanato rūpaŋ" Vism 588; "ruppan' aṭṭhena r." VbhA 3; "rūpa -- rūpaŋ= ruppana sabhāvena yuttaŋ" Cpd. 1567 (where ruppati is, not quite correctly, given as "change"), "ruppatī ti: tasmā rūpan ti vuccati" S iii.86; other defns are "rūpayatī ti rūpaŋ" (with cakkhu & the other 10 āyatanas) VbhA 45; and more scientifically: "paresu rūp' ādisu cakkhu -- paṭihanana lakkhaṇaŋ rūpaŋ" Vism 446. -- Of modern interpretations & discussions see e. g. Dhs. trsl. introd. ch. vi. (pp. 41 -- 63, or 248 -- 71); Dial. ii.244; Expos. 67n; Cpd. 270 sq. (where objections are raised to trsln "form," and as better (philosophical) terms "matter," "material quality" are recommended). See also loka for similar etym. -- B. (lit.) appearance, form, figure Dhs 597 sq. (=form either contrasted with what is unseen, or taken for both seen and unseen), 751; Mhvs 27, 30 (sīha -- vyagghādirūpāni representations of lions, tigers etc.); 30, 68 (ravicanda -- tāra -- rūpāni id.); 36, 31 (loha˚ bronze statue); ThA 257. -- Esp. beautiful form, beauty S iv.275= Pv ii.958 (as one of the 10 attributes, with sadda etc., of distinction: see also below D ii.a); Miln 285; Mhvs 20, 4 (rūpa -- māninī proud of her beauty); PvA 89. -- surūpa very beautiful ThA 72; durūpa of evil form, ugly A ii.203 sq. (dubbaṇṇa+). -- In phrase rūpaŋ sikkhati Vin i.77=iv.129 the meaning is doubtful; it may be "to study drawing, or arts & craft," or (with Mrs. Rh. D.) "weights & measures," or (w. Hardy) "money changing." It is said that through this occupation the eyes become bad; it is opposed to gaṇanā. -- C. ( -- ˚) of such & such a form, like, kind, of a certain condition or appearance. In this appln very frequent & similar to E. -- hood, or Ger. -- heit, i. e. an abstract formation. Often untranslatable because of the latter character. It is similar to kāya (cp. expln of ātura<-> rūpa Vv 8314 by abhitunna -- kāya Vva 328), but not so much with ref. to life & feeling as to appearance and looks. E. g. aneka˚ Sn 1079 (=anekavidha Nd2 54); adissamāna˚ invisible PvA 6 (lit. with invisible form); ummatta˚ as if mad, under the appearance of madness, like a madman Pv i.81; ii.63; eva˚ in such a condition Pv ii.15; tapassī˚ appearing to be an ascetic Pv i.32; tāraka˚ the (shapes of the) stars Dhs 617; deva˚ as a deva PvA 92. Pleonastically e. g. in: anupatta˚ attaining Pv iv.166; taramāna˚ quickly Pv ii.62; yutta˚ fit PvA 157; sucitta˚ variegated Pv i.109. -- Cases ad verbially: citta -- rūpaŋ according to intention Vin iii.161; iv.177; cetabba -- rūpaŋ fit to be thought upon J iv.157. (=˚yuttakaŋ C.). -- atta -- rūpena on my own account S iv.97; godha -- rūpena as an iguana Mhvs 28, 9. -- D. (as philos. t. t.) principle of (material) form, materiality, visibility. -- There are var. groups of psychological and metaphysical systematizations, in which rūpa functions as the material, gross factor, by the side of other, more subtle factors. In all these representations of rūpa we find that an element of moral psychology overshadows the purely philosophical & speculative aspect. A detailed (Abhidhammatic) discussion of rūpa in var. aspects is to be found at Dhs § 585 -- 980. <-> 1. rūpa as āyatana or sense object. It is the object of the activity or sphere of the organ of sight (cakkhu). As such it heads the list of the 6 bāhirāni āyatanāni (see e. g. Nd2 p. 238 A -- E & āyatana3) with "cakkhunā rūpaŋ disvā" (the others: sota>sadda, ghāna>gandha, jivhā>rasa, kāya>phoṭṭhabba, mano>dhamma), cp. cakkhu -- viññeyyā rūpā iṭṭhā kantā etc. D i.245; M i.266; cakkhunā rūpaŋ passati iṭṭha -- rūpaŋ kanta -- rūpaŋ etc. S iv.126; -- see further: Vin i.34 (sabbaŋ ādittaŋ: cakkhuŋ ādittaŋ, rūpa ādittā etc. with sequence of other āyatanas); D ii.308 sq., 336 sq.; M iii.18 (yaŋ kho rūpaŋ paṭicca uppajjati sukhaŋ somanassaŋ, ayaŋ rūpe assādo; cp. Ps ii.109 sq.), 291 (ye te cakkhu -- viññeyyesu rūpesu avīta -- rāgā etc.); Ps i.79; ii.38 (rūpī rūpāni passatī ti vimokkho); Dhs 617, 653, 878; Tikp 28. <-> 2. (metaphysically) as the representative of sensory or material existence: (a) universally as forming the corporeal stratum in the world of appearance or form (rūpa-bhava) as compared with the incorporeal (arūpa -- bhava), being itself above, and yet including the kāma -- bhava. (The kāmabhava is a subdivision of rūpabhava, which has got raised into a third main division.) This triad is also found in combns with loka or dhātu (see dhātu 2 a & d), or avacara. See e. g. D i.17; iii.215 (˚dhātu), 216 (˚bhava); Kvu 370 sq. (˚dhātu); Dhs 499 (˚âvacara), 585 (˚dhātu); Vbh 17 (˚āvacara), 25 (as garu -- pariṇāma & dandha -- nirodha compd with arūpa). A similar sequence rūpa arūpa & nirodha (i. e. nibbāna) in old verses at Sn 755; It 45, 62 (rūpehi arūpā santatarā, arūpehi nirodho santataro). On indriya -- rūpa "faculty as form" see indriya B. -- (b) individually in the sphere of saŋsāra as one (i. e. the material quality) of the substrata of sensory individual existence or the khandhas. They are the 5: rūpa -- kkhandha, vedanā˚, saññā˚, sankhārā˚, viññāṇa˚; otherwise called rūp' ûpādāna -- kkhandha etc. (e. g. D iii.223, 278; Vism 443). See khandha ii. B. -- In this property rūpa consists of 28 subdivisions, viz. the 4 (great) dhātūs (mahābhūtāni or else bhūta -- rūpa primary matter) and 24 upādārūpāni (i. e. derivative forms or accidentals). These are given in extenso in the rūpakkhandha section of the Vism (pp. 443 -- 450), also at Dhs 585; the 24 consist of: cakkhu, sota, ghāna, jivhā, kāya, rūpa, sadda, gandha, rasa, itthindriya, purisindriya, jīvitindriya, hadayavatthu, kāya -- viññatti, vacī -- viññatti, ākāsa -- dhātu, (rūpassa) lahutā mudutā kammaññatā, upacaya santati jaratā aniccatā, kabaḷinkār' -- āhāra; cp. defn at Nett 73: cātu -- mahābhūtikaŋ rūpaŋ catunnaŋ ca mahābhūtānaŋ upādāya rūpassa paññatti. The rūpakkhandha shares with the others the qualities of soullessness, evanescence and ill (anattā, anicca, dukkha); e. g. rūpañ ca h' idaŋ attā abhavissa, na y' idaŋ rūpaŋ ābadhāya saŋvatteyya Vin i.13, cp. similarly M iii.282 sq.; S iii.66; quoted and expld in detail at Vism 610; rūpaŋ aniccaŋ Vin i.14; M i.228; iii.18 (also expld at Vism 610); S iii.48, 66, 88; rūpe anicc' ânupassanā Ps ii.186 sq. -- See also D ii.301; iii.233; Ps i.23, 53, 104; ii.96, 102, 109 (rūpassa ādīnavo); Vbh 1. sq., 12 sq. (in detail); Kvu 11 sq.; Vism 443 sq.; Tikp 33; VbhA 2, 3, 32 sq.=S iii.142 (with var. similes); DhA iv.100. -- (c) in the making up of the individuality as such (nāma -- rūpa), where in contrast with nāma (as abstract, logical, invisible or mind -- factor) rūpa represents the visible (material) factor, resembling kāya (cp. phrase nāma -- kāya in same sense). The foll. are current defns of nāma -- rūpa: nāma -- (kāya)=vedanā, saññā, cetanā, phassa, manasikāra (otherwise citta -- sankhārā), rūpa( -- kāya)=cattāro mahā -- bhūtā catunnaŋ m -- bhūtānaŋ upādāya rūpaŋ (otherwise kāya -- sankhārā) S ii.4; iii.59 sq.; Ps i.183; with explns at Vism 558 & VbhA 169. Defined at Nett 15: "ye phassa -- pañcamakā dhammā: idaŋ nāmaŋ, yāni pañc' indriyāni rūpāni: idaŋ rūpaŋ, tad ubhayaŋ nāmarūpaŋ viññāṇa -- sampayuttaŋ." Discussed in detail also at Vism 562 (=VbhA 173, 174), 587 -- 597; cp. DhsA 392 (Expos. 500, where "mind -- matter" is given as corresp. couple in trsln, do. Cpd. 271 sq. "mind and body"). See also under paṭicca -- samuppāda. -- 3. various references: D iii.102, 212, 225, 244, 273; M i.84 (Gotamo kāmānaŋ pariññaŋ paññāpeti, rūpānaŋ, vedanānaŋ); S ii.198; iii.11 (evaŋ -- rūpo siyaŋ, evaŋ vedano etc.), 101 (id., & the khandhas); Sn 867, 874, 943, 1037, 1121; Nd1 425; Tikp 36, 38, 54, 262; Vism 625 (uppajjanaka˚).
-- ārammaṇa a visible thing as object Dhs 146, 365; DhsA 310 (cp. Expos. 407). -- âvacara world of form, sphere of matter (cp. Expos. 67, 216n, 264) PvA 163. -- ûpaga (satta) (a being) living in (bodily) form It 62; Sn 754. -- ūpajīvinī f. a woman living on her beauty, i. e. a harlot PvA 46, 201. -- ññu knowing (var.) bodily forms M i.220=A v.347. -- taṇhā craving after form D ii.309; iii.216, 244, 280; VbhA 179 (in det.). -- dakkha one clever in forms, viz. an artist (accountant?) Miln 344 (in the Dhamma -- nagara). -- dhātu the element of form, material element Vism 486; Nett 32, 97. See above D 2. -- nimitta sign of form Ps i.92. -- patta beautiful J i.61. -- pamāṇika measuring by form (outward appearance), one of the 4 kinds of measurements which the world takes of the Tathāgata (see A ii.71 & Pug 53), viz. rūpa˚, ghosa˚, lūkha˚, dhamma˚ DhA iii.113; the same four similarly at SnA 242. -- pātubhāva appearance of form (also as ˚antara˚ intermediate form) SnA 245. -- bhava material existence: see above D 2. -- rāga lust after rebirth in rūpa D iii.234 (+arūpa˚); Nett 28 (pañc' indriyāni rūpīni rūpa -- rāgassa padaṭṭhānaŋ. -- rūpa material form (mutable material quality?) Cpd. 156, doubtful trsln & expln -- saññā perception of material qualities, notion of form D i.34; ii.112 (expld in det. at Vism 328); iii.224, 244, 253; Nd2 545; DhsA 200 (cp. Expos. 269). -- saññin perceiving form D iii.260; Ps ii.38; Sn 1113. -- santati duration of material form Vism 431; VbhA 21. -- samussaya accumulation of form, complex form ThA 98. -- samāpatti attainment of beauty J i.406. -- sampatti beauty J iii.187. -- siri personal splendour J i.60.