coma

¹ American  

[koh-muh] / ˈkoʊ mə /

noun

plural

comas

1. a state of prolonged unconsciousness, including a lack of response to stimuli, from which it is impossible to rouse a person.

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coma ² American  

[koh-muh] / ˈkoʊ mə /

noun

plural

comae

1. Astronomy. the nebulous envelope around the nucleus of a comet.

2. Optics. a monochromatic aberration of a lens or other optical system in which the image from a point source cannot be brought into focus, the image of a point having the shape of a comet.

3. Botany.

   1. a tuft of silky hairs at the end of a seed.

   2. the leafy crown of a tree; cluster of leaves at the end of a stem.

   3. a terminal cluster of bracts, as in the pineapple.

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coma ¹ British  

/ ˈkəʊmə /

noun

1. astronomy the luminous cloud surrounding the frozen solid nucleus in the head of a comet, formed by vaporization of part of the nucleus when the comet is close to the sun

2. botany

   1. a tuft of hairs attached to the seed coat of some seeds

   2. the terminal crown of leaves of palms and moss stems

3. optics a type of lens defect characterized by the formation of a diffuse pear-shaped image from a point object

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coma ² British  

/ ˈkəʊmə /

noun

1. a state of unconsciousness from which a person cannot be aroused, caused by injury to the head, rupture of cerebral blood vessels, narcotics, poisons, etc

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coma ¹ Scientific  

/ kō′mə /

plural

comae

1. 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.).

2. Astronomy See more at comet

3. 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.

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coma ² Scientific  

/ kō′mə /

plural

comas

1. A state of deep unconsciousness, usually resulting from brain trauma or metabolic disease, in which an individual is incapable of sensing or responding to external stimuli.

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coma Cultural  

1. An abnormal state of deep unconsciousness. A coma may occur as the result of trauma to the head, disease (such as meningitis, stroke, or diabetes mellitus), or poisoning.

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Other Word Forms

• comal adjective

Etymology

Origin of coma¹

First recorded in 1640–50, coma is from the Greek word kôma deep sleep

Origin of coma²

1660–70; < Latin: hair < Greek kómē

Example Sentences

Following three days in a coma after a seizure, Phoebe, from Cardiff, put her symptoms into the AI chatbot.

From BBC • Apr. 9, 2026

Imagine going into a coma exactly one year ago and waking up a month later.

From The Wall Street Journal • Apr. 1, 2026

Hubble observed K1 breaking into at least four separate fragments, each surrounded by its own coma, the cloud of gas and dust that forms around a comet's icy core.

From Science Daily • Mar. 21, 2026

He managed to escape, but he was placed in a medically induced coma to aid recovery from smoke inhalation and hospitalized for six days.

From Los Angeles Times • Mar. 11, 2026

They never said what they did with people in a coma.

From "The River" by Gary Paulsen

Related Words

• oblivion
• slumber
• stupor
• trance