Pronunciation: (skip'jak"),[key] —n., —pl.(esp. collectively)-jack,(esp. referring to two or more kinds or species)-jacksfor 1;-jacksfor 2, 3. 1. any of various fishes that leap above the surface of the water, as a tuna, Euthynnus pelamis, or the bonito.
2. Entomol.See click beetle. 3. Naut.an American one-masted sailing vessel.