co|ma

co|ma¹ «KOH muh», noun, plural -mas.

1. a prolonged unconsciousness caused by disease, injury, or poison; stupor.

2. Figurative: »

Honour, duty, compassion…are sentiments never in a state of coma (William Gladstone).

╂[< Greek kôma, -atos deep sleep]

co|ma² «KOH muh», noun, plural -mae «-mee».

1. Astronomy. a cloudlike, faintly luminous mass around the nucleus of a comet, consisting of dust particles mixed with frozen water, frozen methane, and frozen ammonia: »

The nuclei of the smaller comets are only a mile or so in diameter, but the visible head, or coma, may extend for thousands of miles beyond it (New Astronomy).

2. Optics. the blurred appearance or hazy border surrounding an object viewed through a lens which is not free from spherical aberration: »

Coma differs from spherical aberration in that a point object is imaged not as a circle, but as a comet-shaped figure, whence the term coma (Sears and Zemansky).

3. Botany. a tuft of hairs at the end of a seed, or a leafy crown, such as that on a palm tree.

╂[< Latin coma < Greek kómē hair of the head, mane; trail of light]