a prefix used freely in English and meaning "not, lack of," or "sham," giving a negative sense to any word, 14c., from Anglo-French noun-, from Old French non-, from Latin non "not, by no means, not at all, not a," from Old Latin noenum "not one" (*ne oinom, from PIE root *ne- "not" + PIE root *oi-no- "one, unique"). In some cases perhaps from Middle English non "not" (adj.), from Old English nan (see not). "It differs from un- in that it denotes mere negation or absence of the thing or quality, while un- often denotes the opposite of the thing or quality" [Century Dictionary].
late 14c., "act of attending to one's duties" (archaic), from Old French atendance "attention, wait, hope, expectation," from atendant, present participle of atendre "expect, wait for; pay attention" (see attend). Meaning "action of waiting on someone" dates from late 14c. (to dance attendance on someone is from 1560s); that of "action of being present, presenting oneself" (originally with intent of taking a part) is from mid-15c. Meaning "number of persons present" is from 1835. To take attendance in a classroom or lecture is by 1891.