Choir
Middle English quer, quere, from Old French quer, from Latin chorus (see chorus). The spelling change in the 17th century was due to association with Latin chorus and modern French choeur .
wiktionary
From Middle Englishquer, quere, from Old French quer, from Latin chorus, from Ancient Greek χορός(khorós, “company of dancers or singers”). Modern spelling influenced by chorus and Modern French chœur. Doublet of chorus.
etymonline
choir (n.)
c. 1300, queor "part of the church where the choir sings," from Old French cuer, quer "(architectural) choir of a church; chorus of singers" (13c., Modern French choeur), from Latin chorus "choir" (see chorus). Meaning "band of singers" in English is from c. 1400, quyre. Re-spelled mid-17c. in an attempt to match classical forms, but the pronunciation has not changed.
