drift off

c.1300, literally "a being driven" (of snow, etc.); not recorded in Old English; either a suffixed form of drive (v.) (cf. thrift/thrive) or borrowed from Old Norse drift "snow drift," or Middle Dutch drift "pasturage, drove, flock," both from Proto-Germanic *driftiz (cf. Danish and Swedish drift, German Trift), from PIE root *dhreibh- "to drive, push" (see drive (v.)). Sense of "what one is getting at" is from 1520s. Meaning "controlled slide of a sports car" attested by 1955.