from the same as 40; properly, clean, i.e. (figuratively) innocent, modest, perfect:
KJV-- chaste, clean, pure.
Inwardly pure. While this purity is inward in nature, it also affects a person's conduct <1 Pet. 3:2>. As commonly understood, the word chaste is applied to sexuality; the chaste person is innocent of sexual impurity, in desire, imagination, and action <2 Cor. 11:2; Titus 2:5>. Some modern translations use the word pure where the KJV uses chaste.
(from Nelson's Illustrated Bible Dictionary)
(Copyright (C) 1986, Thomas Nelson Publishers)