A state of profound insensibility from which it is difficult or impossible to rouse a person. See Carus.
- A state of deep, often prolonged unconsciousness, usually the result of injury, disease, or poison, in which an individual is incapable of sensing or responding to external stimuli and internal needs.
- Astronomy The nebulous luminescent cloud containing the nucleus and constituting the major portion of the head of a comet.
- Botany A usually terminal tuft or cluster, especially a tuft of hairs on a seed, as on a willow or milkseed.
- Physics A diffuse, comet-shaped image of a point source of light or radiation caused by aberration in the optical system.