Trio

google

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early 18th century: from Italian, from Latin tres ‘three’, on the pattern of duo .

wiktionary

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1715-25; borrowing from Italian trio.

etymonline

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trio (n.)

1724, "composition for three voices," from French trio (c. 1600), from Italian trio, from tri- "three" (see three); patterned on duo. Meaning "group of three persons" is from 1789.