1. Any of several machines or devices, especially:

• A machine for hoisting or moving heavy objects.
• A pile driver.
• A snare or trap for game.
• A pump operated by a windmill.

2. To remove the seeds from (cotton) with a cotton gin.
3. Etymology: from Old French gin, "machine, device, scheme" a form of engin, "skill, cleverness" and "war machine"; from Latin ingenium, "inborn qualities, talent", from in-, "in" + gen-, root of gignere, "to beget, to produce".

At first (about 1200) the meaning referred more to "a trick" or "device" or "any machine"; especially, "military" or the sense of "someone who converts energy to mechanical power" (in the 18th century) particularly with reference to steam engines.