A manger is a trough or box of carved stone or wood construction used to hold food for animals (as in a stable). Mangers are mostly used in livestock raising. They are also used to feed wild animals, e.g., in nature reserves. The word comes from the French manger (meaning "to eat"), from Latin manducare (meaning "to chew").
A "dog in a manger" is a derogatory term referring to someone who keeps others from having or enjoying something that he himself does not want or cannot use.