Definition of Coma

Noun: coma (comas,comae) kow-mu

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