Untie

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Old English untīgan (see un-2, tie).

wiktionary

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From Middle English untien, unteyen, untyȝen, untiȝen, from Old English untīġan(“to untie”), equivalent to un- +‎ tie.

etymonline

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untie (v.)

Old English untigan "loosen, unchain," from un- (2) "opposite of" + tie (v.). Related: Untied; untying.