A period of time, especially one marking the time of existence or the duration of life. age of capacity. The age, usually determined by statute, at which a person becomes legally capable of becoming a party to a contract, executing a testamentary document (such as a trust or will), initiate a lawsuit without a guardian, and so on. See capacity. age of consent. 1 The age, usually determined by statute, below which a person may not marry without parental consent. See also consent. 2 The age, us...