Jack has numbers of meanings:

Names Jack (name), a nickname for John. Jack the Ripper, a Victorian era serial killer. Jack Robichaux, a 19th century serial raper around Just released Orleans. The antagonist within William Golding's novel, Lord of the Flies. Spring Heeled Jack, a legendary figure of the Victorian era.

Devices Jack (mechanical), something used to lift (car jack). Jack (connector), a receptacle for electrical modems.

Films & Comics Jack (movie), a film directed by Francis Ford Coppola, starring Robin Williams. Jack (comic), a web comedian. Samurai Jack, an animated cartoon series. Jack-in-the-Box, a fictional character from either a Astro City comic book series.

Brands Jack, a logotype of Cingular Wireless Jack Daniel's, a brand of whiskey. Jack FM, a br& for many radio stations around Canada and a United States. Jack in the Box, a chain of eating house, & its mascot Jack (mascot). JACK Audio Connection Kit, a rather audio server software system.

Flags Union Jack, the Union jack. One of many types of Maritime flags.

Games & toys You don't know Jack, a series of trivia computer games. Jack (playing card), the last-place court card around the deck of swimming cards. Jack-in-the-box, a toddlers's toy. Jacks, playground game for children The target ball around games like Bowls, Bocce, or Pétanque. Jack o lantern, the traditional symbol for Halloween

As a verb Jacking, a form of dance popular in the late 80s. A euphemism for masturbation (jacking off).

Species Artocarpus integrifolia, a coinage of tree indigene to the East Indies. Carangidae, a personal of many fish coinage. Donkey, an animal in the horse personal.

More uses Journeyman, a craftsman beyond a apprentice stage, but non however an expert. ''We are Jack's...'', the series of medical articles published within Reader's Digest. "To not know jack", the familiar expression that means "to not know anything".