Simple vow

In Roman Catholic canon law, a simple vow is any vow, public or private, individual or collective, concerned with an action or with abstaining from an action, if that vow has not been recognized by the Church as a solemn vow.

Even a vow accepted by a legitimate superior in the name of the Church (the definition of a "public vow") is a simple vow if the Church has not granted it recognition as a solemn vow.