self-conscious adj.

word forming element indicating "oneself," also "automatic," from Old English use of self (pron.) in compounds, such as selfbana "suicide," selflice "self-love, pride, vanity, egotism," selfwill "free will." Middle English had self-witte "one's own knowledge and intelligence" (early 15c.).

OED counts 13 such compounds in Old English. Middle English Compendium lists four, counting the self-will group as a whole. It re-emerges as a living word-forming element mid-16c., "probably to a great extent by imitation or reminiscence of Greek compounds in (auto-)," and formed a great many words in the pamphlet disputes of the 17c.

c. 1600, "knowing, privy to" (poetic), from Latin conscius "knowing, aware," from conscire "be (mutually) aware," from assimilated form of com "with," or "thoroughly" (see con-) + scire "to know" (see science). The Latin word probably is a loan-translation of Greek syneidos.

The sense of "knowing or perceiving within oneself, sensible inwardly, aware" is from 1630s, perhaps a shortening of conscious to oneself (1620s). Also compare the Latin sense evolution in conscience. From 1650s as "aware (of a fact)." Sense of "active and awake, endowed with active mental faculties" is from 1837. Related: Consciously.