External

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late Middle English: from medieval Latin, from Latin exter ‘outer’.

wiktionary

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From Late Middle English, from Medieval Latin externus(“outward, external”), from exter/ exterus(“on the outside, outward”).

etymonline

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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.