adrift (adv.)

prefix or inseparable particle, a conglomerate of various Germanic and Latin elements.

In words derived from Old English, it commonly represents Old English an "on, in, into" (see on (prep.)), as in alive, above, asleep, aback, abroad, afoot, ashore, ahead, abed, aside, obsolete arank "in rank and file," etc., forming adjectives and adverbs from nouns, with the notion "in, at; engaged in." In this use it is identical to a (2).

It also can represent Middle English of (prep.) "off, from," as in anew, afresh, akin, abreast. Or it can be a reduced form of the Old English past participle prefix ge-, as in aware.

Or it can be the Old English intensive a-, originally ar- (cognate with German er- and probably implying originally "motion away from"), as in abide, arise, awake, ashamed, marking a verb as momentary, a single event. Such words sometimes were refashioned in early modern English as though the prefix were Latin (accursed, allay, affright are examples).

In words from Romanic languages, often it represents reduced forms of Latin ad "to, toward; for" (see ad-), or ab "from, away, off" (see ab-); both of which by about 7c. had been reduced to a in the ancestor of Old French. In a few cases it represents Latin ex.

[I]t naturally happened that all these a- prefixes were at length confusedly lumped together in idea, and the resultant a- looked upon as vaguely intensive, rhetorical, euphonic, or even archaic, and wholly otiose. [OED]

early 14c., literally "a being driven" (at first of snow, rain, etc.); not recorded in Old English, it is either a suffixed form of drive (v.) (compare thrift/thrive) or borrowed from Old Norse drift "snow drift," or Middle Dutch drift "pasturage, drove, flock," both from Proto-Germanic *driftiz (source also of Danish and Swedish drift, German Trift), from PIE root *dhreibh- "to drive, push" (see drive (v.)).

"A being driven," hence "anything driven," especially a number of things or a heap of matter driven or moving together (mid-15c.). Figurative sense of "aim, intention, what one is getting at" (on the notion of "course, tendency") is from 1520s. Nautical sense of "deviation of a ship from its course in consequence of currents" is from 1670s. Meaning "controlled slide of a sports car" attested by 1955.