uniat

noun

1. a member of an Eastern church that is in union with the Roman Catholic Church, acknowledges the Roman pope as supreme in matters of faith, but maintains its own liturgy, discipline, and rite.

adjective

1. designating any of the Eastern Churches that retain their own liturgy but submit to papal authority

noun

2. a member of one of these Churches

“pertaining to an Eastern Christian church that acknowledges the supremacy of the Pope,” 1833, from Russian uniyat, from unia “unity, union,” from Latin unus “one” (see one).