1. The celestial orb which revolves round the earth; the satellite of the earth; a secondary planet, whose light, borrowed from the sun, is reflected to the earth, and serves to dispel the darkness of night. The diameter of the moon is 2,160 miles, its mean distance from the earth is 240,000 miles, and its mass is one eightieth that of the earth. See lunar month, under Month. The crescent moon, the diadem of night. (Cowper)
2. A secondary planet, or satellite, revolving about any member of the solar system; as, the moons of jupiter or saturn.
3. The time occupied by the moon in making one revolution in her orbit; a month.
4. A crescentlike outwork. See half-moon. Moon blindness.
(Science: medicine) hemeralopia. Moon dial, a dial used to indicate time by moonlight. Moon face, a round face like a full moon. Moon madness, lunacy. Moon month, a lunar month.
(Science: botany) Moon trefoil, a shrubby species of medic (Medicago arborea). See Medic. Moon year, a lunar year, consisting of lunar months, being sometimes twelve and sometimes thirteen.
Origin: OE. Mone, AS. Mona; akin to D. Maan, OS. & OHG. Mano, G. Mond, Icel. Mani, Dan. Maane, Sw. Mane, Goth. Mena, Lith. Men, L. Mensis month, Gr. Moon, month, Skr. Mas moon, month; prob. From a root meaning to measure (cf. Skr. Ma to measure), from its serving to measure the time. 271. Cf. Mete to measure, Menses, Monday, Month.