UK, slangHeroin tablets (from "jacks and jills" = pills)
“As soon as Barry swung the machete at his head, Vince snapped the PSF knife out of his pocket with his right hand and the jacks from his pocket with his left.”
uncountableA children's game involving picking up objects; knucklebones; jackstones.
“The rest of the day he heard the children playing kick-the-can, hide-and-seek, Over-Annie-Over, jacks, tops, mibs, and the sound of the little monsters in every shrub and shadow would not let him rest”
form-of, pluralplural of Jack
name
A surname originating as a patronymic derived from Jack.