Detach

google

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late 16th century (in the sense ‘discharge a gun’): from French détacher, earlier destacher, from des- (expressing reversal) + attacher ‘attach’.

wiktionary

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From Old French destachier, from the same root as attach; compare French détacher and Portuguese and Spanish destacar.

etymonline

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detach (v.)

1680s, "unfasten, disunite" (transitive), especially "separate for a special purpose or service," from French détacher "to detach, untie," from Old French destachier, from des- "apart" (see des-) + attachier "attach" (see attach). Related: Detached; detaching.