Used only in Galatians 4:24, where the apostle refers to the history of Isaac the free-born, and Ishmael the slave-born, and makes use of it allegorically.
Every parable is an allegory. Nathan (2 Samuel 12:1-4) addresses David in an allegorical narrative. In the eightieth Psalm there is a beautiful allegory: "Thou broughtest a vine out of Egypt," etc. In Ecclesiastes 12:2-6, there is a striking allegorical description of old age.