Jack

a familiar form of John, the most widely spread of Christian names, and said to be derived from the French Jacques or, as others maintain, from Jankin , a distinctive form of Johan or John ; Johnkin gives us Jock and Jockey ; from its extreme commonne it has acquired that slightly contemptuous signification observable in such compounds as "every man Jack ," " Jack -of-all-trades," " Jack -an-apes," and the name as applied to the knaves in playing-cards, and to the small white ball used as a mark in the game of bowls is an example of its transferred sense.