Sail

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.
4. A trip in a boat, especially a sailboat.

   "Let's go for a sail."

5. (plural "sail") A sailing vessel; a vessel of any kind; a craft.

   "Twenty sail were in sight."