plural of photon sail

(astronautics) a solar sail.

plural of light 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.

plural of point of sail

(nautical) A technique for navigation using planar geometry. / (nautical, proscribed) A technique for navigation using the assumption the Earth is flat.

(idiomatic, uncountable) Used to describe an activity that is not encountering any problems.

plural of working sail

To pass or progress quickly and easily.