coma (Noun) — A state of deep and often prolonged unconsciousness; usually the result of disease or injury.
coma (Noun) — (botany) a usually terminal tuft of bracts (as in the pineapple) or tuft of hairs (especially on certain seeds).
coma (Noun) — (astronomy) the luminous cloud of particles surrounding the frozen nucleus of a comet; forms as the comet approaches the sun and is warmed.
coma (Noun) — (optics) an aberration giving a V-shaped flare to an image (e.g. a star in an astronomical observation).