coma
n.-
1 unconsciousness (n.) B2 Upper Intermediate Medicinea deep state of sleep-like unconsciousness that lasts for a long time, usually caused by a serious injury or illness.
a state of deep and often prolonged unconsciousness, typically resulting from severe trauma, disease, or intoxication.
ExampleThe driver remained in a coma for two weeks after the car accident.
ExampleMedical staff monitored his brain activity closely while he remained in a medically induced coma to allow his injuries to heal.
UsageOften used with the verbs 'fall into', 'go into', or 'be in'.
- insensibility
- trance
- consciousness
- wakefulness
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2 comet cloud (n.) C2 Proficiency Technical Sciencethe glowing cloud of gas and dust that surrounds the center of a comet.
the nebulous envelope of gas and dust surrounding the nucleus of a comet, formed when the comet passes close to the sun.
ExampleAs the comet got closer to the sun, its coma became much brighter.
ExampleThe spacecraft flew through the coma to collect dust samples, providing researchers with data on the chemical composition of the early solar system.
UsageUsually refers specifically to the head of the comet excluding the nucleus.
Teacher's tipThis is a highly specialized term; students are unlikely to encounter it outside of astronomy texts.
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3 plant tuft (n.) C2 Proficiency Technical Sciencea bunch of hairs or leaves at the end of a seed or a branch.
a tuft of hairs on a seed, or a cluster of leaves or branches at the apex of a plant structure.
ExampleThe seeds of the plant are topped with a silky coma that helps them float in the wind.
ExampleThe botanist identified the species by the distinct shape of the coma attached to the seeds.
UsageUsed as a technical term in botanical descriptions.
- tuft
- cluster
Learned borrowing from Ancient Greek κῶμα (kôma, “deep sleep”).
Learned borrowing from Latin coma (“hair of the head”), from Ancient Greek κόμη (kómē, “hair”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Last updated June 20, 2026