The story
- Englisha-
- Proto-Germanic*drībaną
- Proto-Germanic*driftiz
- Old English*drift
- Middle Englishdrift
- Englishdrift
- English todayadrift
The adverb is derived from a- (prefix meaning ‘at; in; on’ showing conditions, manners, or states) + drift (noun), probably modelled after afloat. The adjective is probably derived from the adverb, as it is attested later.
Etymology from Wiktionary, CC BY-SA 4.0.