(by extension) simple, straightforward, or easy

(geometry) A catenary-generated curve in the form of a cross-section of a sail filled by wind.

plural of sailing ship

To depart on a voyage by boat.

plural of sailing vessel

(nautical) A diagram showing the number, possible arrangements, and sizes of the sails for a sailing vessel

(idiomatic, nautical) With sails unfurled; powered by the wind. / In motion.

(astronautics) a solar sail.

(astronautics) A sail-like structure on a spacecraft consisting of enormous ultrathin mirrors, propulsion being achieved by the radiation pressure of light from a star or laser.

(astronautics) A solar sail.