Comae

Part of speech: noun

Definitions

1. A type of hair or tuft found on the heads of certain celestial beings or organisms
2. An ancient term referring to the hair of a goddess or divinity in mythology
3. A scientific term used in astronomy to describe the atmosphere surrounding a comet's nucleus

Etymology: "Comae" is the plural of "coma," and the two words share a surprising pair of meanings: one for a sleeper's stupor and one for a head of hair. The Ancient Greek "kômea" meant deep sleep, while the related "kómē" meant hair of the head, and English took the hair sense through Latin "coma" in the sense of a head of hair. The astronomical use depends on that hair sense. A comet's glowing envelope around its nucleus looks like a fuzzy, hair-like halo, so the same Greek root that gave Latin its word for tresses gave astronomers a term for this cloud. Because the root was already on hand, the image came from the word, not the other way round. The plural form "comae" follows the Latin pattern, with the "-ae" ending that many Latin nouns in "-a" take. Astronomers use it whenever they discuss more than one comet's halo.

Synonyms: hair, corona