A jig is a fast, lively folk dance with a bouncy rhythm, often connected to Irish or Scottish music, and also the name for the music itself. In workshops, a jig is a different thing entirely: a tool that holds a piece of work steady and guides another tool, so you can repeat the exact same cut, hole, or shape many times. There's also the fixed phrase "the jig is up," meaning someone's secret plan or trick has just been discovered.