(New Age) A mythical dangerous belt of photons emanating from the Pleiades that will collide with the Earth in the near future according to New Age mystics.

(of a black hole) Synonym of photon sphere

(of a black hole) A region of around a black hole where photons travel in orbits around the singularity, just beyond the event horizon.

(astronautics) a solar sail.

plural of photon sail

A periodic optical nanostructure that affects the motion of photons in much the same way that ionic lattices affect electrons in solids.

(physics) A photon, whose energy is too small to be detected, that is one of a cloud associated with a charged particle.

plural of photon sphere

(physics, figuratively) A photonic Bose-Einstein condensate, comprised of thousands of photons sufficiently concentrated and cooled in an optical well.

(physics, rare) A theoretical but not yet detected particle proposed to explain, among other things, the mechanisms of gravity; a gauge boson.