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A sleeved outer vestment reaching to the knees, worn over the alb by a subdeacon or sometimes under the dalmatic by a bishop or cardinal. Also called tunic.
[Middle English, from Latin tunicula, diminutive of tunica, tunic; see tunic.]
(Roman Catholic Church) chiefly RC Church the liturgical vestment worn by the subdeacon and bishops at High Mass and other religious ceremonies
[C14: from Latin tunicula a little tunic]
tu•ni•cle(ˈtu nɪ kəl, ˈtyu-)
a vestment worn over the alb by subdeacons, as at the celebration of the Mass, and by bishops.