noun the envelope of a comet; a nebulous covering, which surrounds the nucleus or body of a comet.
2. coma ·noun a state of profound insensibility from which it is difficult or impossible to rouse a person. ·see carus.
3. coma ·noun a tuft or bunch, as the assemblage of branches forming the head of a tree; or a cluster of bracts when empty and terminating the inflorescence of a plant; or a tuft of long hairs on certain seeds.