1. In a harpsichord, clavichord, or virginal, the jack is the device attaching the plectrum to the key, enabling the depression of the key to cause the plectrum to pluck the string. 2. In a piano, the jack is the pivoted, vertical lever that causes the hammer to rise when a key is depressed.
- A mechanical device used to lift heavy loads.
- (card games) The card ranking between the ten and queen of any suit, picturing a knave or prince on its face. In some card games has a value of eleven based on its rank, but in many card games has a value of ten like the ten , queen , and king cards. Also called a knave .