Unite

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late Middle English: from Latin unit- ‘joined together’, from the verb unire, from unus ‘one’.

wiktionary

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Borrowed from Latin ūnītus, perfect passive participle of ūniō.

etymonline

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unite (v.)

early 15c. (transitive), from Late Latin unitus, past participle of unire "to unite, make into one" (transitive), from Latin unus "one" (from PIE root *oi-no- "one, unique"). Intransitive sense from 1610s. Related: United; uniting.