A, as a prefix to English words, is derived from various sources.
(1) It frequently signifies on or in (from an, a forms of AS. on),
denoting a state, as in afoot, on foot, abed, amiss, asleep, aground,
aloft, away (AS. onweg), and analogically, ablaze, atremble, etc. (2)
AS. of off, from, as in adown (AS. ofd/ne off the dun or hill). (3) AS.
a- (Goth. us-, ur-, Ger. er-), usually giving an intensive force, and
sometimes the sense of away, on, back, as in arise, abide, ago. (4) Old
English y- or i- (corrupted from the AS. inseparable particle ge-,
cognate with OHG. ga-, gi-, Goth. ga-), which, as a prefix, made no
essential addition to the meaning, as in aware. (5) French a (L. ad
to), as in abase, achieve. (6) L. a, ab, abs, from, as in avert. (7)
Greek insep. prefix / without, or privative, not, as in abyss, atheist;
akin to E. un-.