We don't have synonyms for cosmic rays yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are cosmic ray and cosmic-ray.
(n) :
(astronomy) Any of a range of subatomic particles, and thus also electromagnetic waves, that permeate the universe owing to their various origins within stars or from collisions outside stars. (Life on Earth is mostly shielded from them by the Earth's magnetic field, but a small amount strikes us all each day.)
(n) :
(astronomy) Any of a range of subatomic particles, and thus also electromagnetic waves, that permeate the universe owing to their various origins within stars or from collisions outside stars. (Life on Earth is mostly shielded from them by the Earth's magnetic field, but a small amount strikes us all each day.)