Verb

1. To change tack with the wind crossing behind the boat. (Mostly used of boats and other small sailing craft — the corresponding manoeuver in a sailing ship is to wear.)
2. To shift a fore-and-aft sail suddenly and forcefully from one side to the other, while sailing before the wind. (also jibe.)
3. To sneer (see gibe.)
4. gybe at: to hesitate, vacillate, or balk when faced with a proposal, plan, or course of action. (Obsolete)

Noun

1. The act of gybing.
2. A sudden shift of a sail's angle, or a sudden change in the direction that a boat is sailing.
3. A sudden change in direction or approach; vacillation.
4. A sneer. (see gibe.)