(more at http://dsal.uchicago.edu/cgi-bin/philol ... :1470.pali)Viññāṇa (nt.) [fr. vi+jñā; cp. Vedic vijñāna cognition] (as special term in Buddhist metaphysics) a mental quality as a constituent of individuality, the bearer of (individual) life, life -- force (as extending also over rebirths), principle of conscious life, general consciousness (as function of mind and matter), regenerative force, animation, mind as transmigrant, as transforming (according to individual kamma) one individual life (after death) into the next. (See also below, c & d). In this (fundamental) application it may be characterized as the sensory and perceptive activity commonly expressed by "mind." It is difficult to give any one word for v., because there is much difference between the old Buddhist and our modern points of view, and there is a varying use of the term in the Canon itself. In what may be a very old Sutta S ii.95 v. is given as a synonym of citta (q. v.) and mano (q. v.), in opposition to kāya used to mean body. This simpler unecclesiastical, unscholastic popular meaning is met with in other suttas. E. g. the body (kāya) is when animated called sa -- viññāṇaka (q. v. and cp. viññāṇatta). Again, v. was supposed, at the body's death, to pass over into another body (S i.122; iii.124) and so find a support or platform (patiṭṭhā). It was also held to be an immutable, persistent substance, a view strongly condemned (M i.258). Since, however, the persistence of v. from life to life is declared (D ii.68; S iii.54), we must judge that it is only the immutable persistence that is condemned. V. was justly conceived more as "minding" than as "mind." Its form is participial. For later variants of the foregoing cp. Miln 86; PvA 63, 219.
Now compare with a definition of 'consciousness':
Definition of CONSCIOUSNESS
: the totality in psychology of sensations, perceptions, ideas, attitudes, and feelings of which an individual or a group is aware at any given time or within a given time span <altered states of consciousness, such as sleep, dreaming and hypnosis—Bob Gaines>
: waking life (as that to which one returns after sleep, trance, or fever) in which one's normal mental powers are present <the ether wore off and the patient regained consciousness>
: the upper part of mental life of which the person is aware as contrasted with unconscious processes (http://www.merriam-webster.com/medical/consciousness)
'Consciousness' as a translation for 'Viññāṇa' led to literally years of misunderstandings and thus angst for me, as I grappled with some of the finer points of the Buddha's teaching. I am aware that it is translated as such by Venerable Thanissaro, who is greatly important to me as a spiritual guide , as well as by others, so of course I am not being critical of those who have used this term! But I now consider, that much hand-wringing over particular doctrinal issues here could have been avoided, if we stopped thinking of vinnana as merely that which lies within our current scope of conscious awareness, because going by the above definition it is much wider in scope than that.
One point is, that while consciousness as per the English definition is absent during deep sleep, vinnana is present during deep sleep, because if it were not present, the body would cease to function and die. As I understand it, this physical body and vinnana are both needed for life to continue here:
"'From consciousness as a requisite condition comes name-and-form.' Thus it has been said. And this is the way to understand how from consciousness as a requisite condition comes name-and-form. If consciousness were not to descend into the mother's womb, would name-and-form take shape in the womb?"
"If, after descending into the womb, consciousness were to depart, would name-and-form be produced for this world?"
"If the consciousness of the young boy or girl were to be cut off, would name-and-form ripen, grow, and reach maturity?"
"Thus this is a cause, this is a reason, this is an origination, this is a requisite condition for name-and-form, i.e., consciousness."
"'From name-and-form as a requisite condition comes consciousness.' Thus it has been said. And this is the way to understand how from name-and-form as a requisite condition comes consciousness. If consciousness were not to gain a foothold in name-and-form, would a coming-into-play of the origination of birth, aging, death, and stress in the future be discerned?
"Thus this is a cause, this is a reason, this is an origination, this is a requisite condition for consciousness, i.e., name-and-form.
"This is the extent to which there is birth, aging, death, passing away, and re-arising. This is the extent to which there are means of designation, expression, and delineation. This is the extent to which the sphere of discernment extends, the extent to which the cycle revolves for the manifesting (discernibility) of this world — i.e., name-and-form together with consciousness.
It would appear to me that you can't have one without the other. Thus, a person in deep sleep, although unaware, is not without vinnana. But unfortunately, the English definition of 'consciousness' tends to be very similar to 'awareness', ie a wakeful and present state of mind, as opposed to an 'unconscious' one.
I hope this post acts as a springboard for anyone who has found themselves confuted and confused (as I have been) due to the difficulty of finding one English term for vinnana, to do some further research. Since vinnana remains present here, along with this body, from the moment we arose in our mother's womb till the final moment of this current life, it is clear that there are many, many moments where we are quite unaware of it, and that there are levels of it that we currently have little or no access to (for example, we cannot by force of will control many of the body's basic, vital functions - they go on without our conscious involvement; but they could not continue on without vinnana.) It would appear that vinnana is much more than *just* that which knows an object in the here-and-now, our 'conscious awareness', and to conflate the two as identical must lead to much confusion and misunderstanding.