Monastic chastity is a freely received vocation of celibacy and purity through which body and soul are dedicated to Christ.
Chastity is understood as a gift and calling, not merely the absence of marriage. It includes purity of thought, conduct, relationships, and intention. Through prayer and spiritual discipline, the monk or nun seeks an undivided heart and faithful love for God.
The Church does not teach that every Christian must follow this vocation; it is embraced by those called to offer their lives through consecrated celibacy.
Official source: The Three Vows of Monasticism: Chastity.