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

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

From The Wall Street Journal

He was in a coma for two months and was showing no sign of brain activity until his family took his French horn to his bedside, and he started responding to the music.

From BBC

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

Mark McNamee did not know he had meningitis until he woke up in hospital after being in an induced coma.

From BBC

He was in an induced coma for five days following the collision.

From Los Angeles Times

Related Words

• oblivion
• slumber
• stupor
• trance