noun

1. A piece of fabric attached to a boat and arranged such that it causes the wind to drive the boat along. The sail may be attached to the boat via a combination of mast, spars and ropes.

2. (nautical,uncountable) The concept of a sail or sails, as if a substance.

   “Take in sail: a storm is coming.”

3. The power harnessed by a sail or sails, or the use of this power for travel or transport.