A jib is a sail at the front of a sailboat. The triangle-shaped jib hangs in front of the boat's mast.
Some sailboats use only a jib to move, but most of them combine a main sail, which does most of the work, and a jib, which makes the boat more stable. Jib is also a verb, meaning "move to the opposite side of the ship" or "refuse to follow instructions." The old-fashioned compliment "I like the cut of your jib," or "I like the way you look," comes from nautical slang, in which jib meant "face."