A monk is a person who practices religious asceticism by monastic living, either alone or with any number of other monks. A monk may be a person who decides to dedicate their life to serving other people and serving God or to be an ascetic who voluntarily chooses to leave mainstream society and live their life in prayer and contemplation. The concept is ancient and can be seen in many religions and in philosophy. In the Greek language, the term can apply to women, but in modern English, it is mainly in use for men. The word nun is typically used for female monastics.

Source: Wikipedia