Clerical celibacy in the Catholic Church
Clerical celibacy is the discipline within the Catholic Church by which only unmarried men are ordained to the priesthood in the Latin Church (one of the 24 sui iuris churches of the Catholic Church with some particular exception and in some autonomous particular Churches), and similarly to the diaconate. In other sui iuris (autonomous) particular churches, the discipline applies only to the episcopate.
Source: Wikipedia — Clerical celibacy in the Catholic Church (CC BY-SA 4.0)