Forbids all voluntary sexual pleasure. It constitutes a matrimonial impediment. If the vow be a simple one, which may be anyone of four kinds (of virginity, of not marrying, of receiving Sacred Orders, or of entering religion), it is a hindering impediment, rendering a marriage unlawful although valid, unless a dispensation be obtained. If the vow be solemn, which means that it is made publicly and for life in a religious community wherein such vows are administered, it constitutes a diriment impediment. In certain other communities which have received a special permission from the Holy See to that effect, simple vows would cause a diriment impediment. In either case a dispensation may be given by the Church. The reception of Sacred Orders (that is, of the first of the major orders, which, in our Latin Rite, is subdeaconship) imposes a solemn vow of chastity; and while the Church has the power of dispensing from this, this has been very seldom done.
1909 Catholic Dictionary