subdeacon n a clergyman an order below deacon; one of the Holy Orders in the unreformed western Christian church and the eastern Catholic Churches but now suppressed in the Roman Catholic Church Usage(s) So was the 'deacon and the subdeacon. A subdeacon brought only one large book, explaining that the lectors kept the rest. The celebrant passed in a rich red damask chasuble, followed by a deacon and a subdeacon in dalmatic and tunic.