User

wiktionary

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From Middle English usere, equivalent to use +‎ -er. Cognate with Scots usar, uiser(“user”).

etymonline

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user (n.)

c. 1400, agent noun from use (v.). Of narcotics, from 1935; of computers, from 1967. User-friendly (1977) is said in some sources to have been coined by software designer Harlan Crowder as early as 1972.