use mid-13c., from . user "use, employ, practice," from . *usare "use," frequentative form of pp. stem of L. uti "to use," in Old L. oeti "use, employ, exercise, perform," of unknown origin. Replaced . brucan (see brook (v.)). Used "second-hand" is recorded from 1590s. User is recorded from 1935 in the narcotics sense, 1967 in the computer sense. User-friendly (1977) is said in some sources to have been coined by software designer Harlan Crowder as early as 1972. Verbal phrase used to "formerly did or was" (as in I used to love her) represents a construction attested from , and ... common from , but now surviving only in past tense form. The pronunciation is affected by the t- of to.
Old English hwæt , from Proto-Germanic *khwat (cf. Old Saxon hwat , Old Norse hvat , Danish hvad , Old Frisian hwet , Dutch wat , Old High German hwaz , German was , Gothic hva "what"), from PIE *qwod , neuter singular of *qwos "who" (see who ).
Meaning "what did you say?" is recorded from ; as an interrogative expletive at the end of sentences it is first recorded 1785, common early 20c. in affected British speech. Or what as an alternative end to a question is first attested 1766. "To give one what for is to respond to his remonstrant what for? by further assault" [Weekley]. The phrase is attested from 1873. What's-his-name for "unspecified person" is attested from 1690s; variant whatsisface is first recorded 1967. What's up? "what is happening?" first recorded 1881.