coma definition by Webster's New World
- deep, prolonged unconsciousness caused by injury or disease
- a condition of stupor or lethargy
Origin: Modern Latin ; from Classical Greek kōma (gen. kōmatos), deep sleep ; from Indo-European base an unverified form keme-, to grow tired from source Sanskrit śamītē, to work, prepare, Classical Greek kamatos, fatigue, effort
- Astron. a comet's gaseous cloud surrounding the solid nucleus and forming, with the nucleus, the comet's head
- a bunch of branches, as on the top of some palm trees
- a terminal cluster of bracts on a flowering stem, as in pineapples
- a tuft of hairs at the end of certain seeds
- Photog. a blur caused by the spherical aberration of oblique rays of light passing through a lens
Origin: Classical Latin hair of the head, foliage ; from Classical Greek komē, hair
coma definition by American Heritage Dictionary
noun pl. co·mas
Origin: Greek kōma, deep sleep.
noun pl. co·mae
- 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.
Origin: Latin, hair, from Greek komē.
- coˈmal adjective
coma - Cultural Definition
coma - Medical Definition
coma - Science Definition
Plural comae comae
- Astronomy The brightly shining cloud of gas that encircles the nucleus and makes up the major portion of the head of a comet near the Sun. As a comet moves along its orbit away from the Sun, the gas and dust of the coma dissipate, leaving only the nucleus. A coma can have a diameter of up to 100,000 km (62,000 mi.). See more at comet.
- Physics A diffuse, comet-shaped image of a point source of light or radiation caused by aberration in a lens or mirror. The image appears progressively elongated with distance from the center of the field of view.