"Trouble, a valley near Jericho, so called in consequence of the" "trouble which the sin of Achan caused Israel (Josh. 7:24, 26)." "The expression "valley of Achor" probably became proverbial for" "that which caused trouble, and when Isaiah (Isa. 65:10) refers" "to it he uses it in this sense: "The valley of Achor, a place" "for herds to lie down in;" i.e., that which had been a source of" calamity would become a source of blessing. Hosea also (Hos. "2:15) uses the expression in the same sense: "The valley of" "Achor for a door of hope;" i.e., trouble would be turned into" "joy, despair into hope. This valley has been identified with the" Wady Kelt.

See where Achor occurs in the Bible...

Definition of Achor: