"outsider," c. 1600, from French externe "outer, outward;" as a noun, "a day-scholar," from Latin externus "outside," also used as a noun (see external). As an adjective in English from 1530s.
Entries linking to extern
external adj.
early 15c., "overt;" by 1590s as "situated or lying outside," from Latin externus "outside, outward" (from exterus; see exterior) + -al (1). This version won out over exterial. Related: Externally.