Lunar month :  n : the period between successive new moons (29.531 days) [syn: moon, lunation, synodic month]

Lunar \Lu"nar\, a. [L. lunaris, fr. luna the moon. See Luna, and cf. Lunary.] 1. Of or pertaining to the moon; as, lunar observations. 2. Resembling the moon; orbed. --Dryden. 3. Measured by the revolutions of the moon; as, a lunar month. 4. Influenced by the moon, as in growth, character, or properties; as, lunar herbs. --Bacon. Lunar caustic (Med. Chem.), silver nitrate prepared to be used as a cautery; -- so named because silver was called luna by the ancient alchemists. Lunar cycle. Same as Metonic cycle. See under Cycle. Lunar distance, the angular distance of the moon from the sun, a star, or a planet, employed for determining longitude by the lunar method. Lunar method, the method of finding a ship's longitude by comparing the local time of taking (by means of a sextant or circle) a given lunar distance, with the Greenwich time corresponding to the same distance as ascertained from a nautical almanac, the difference of these times being the longitude. Lunar month. See Month. Lunar observation, an observation of a lunar distance by means of a sextant or circle, with the altitudes of the bodies, and the time, for the purpose of computing the longitude. Lunar tables. (a) (Astron.) Tables of the moon's motions, arranged for computing the moon's true place at any time past or future. (b) (Navigation) Tables for correcting an observed lunar distance on account of refraction and parallax. Lunar year, the period of twelve lunar months, or 354 days, 8 hours, 48 minutes, and 34.38 seconds.

Month \Month\, n. [OE. month, moneth, AS. m[=o]n?, m[=o]na?; akin to m[=o]na moon, and to D. maand month, G. monat, OHG. m[=a]n[=o]d, Icel. m[=a]nu?r, m[=a]na?r, Goth. m[=e]n[=o]?s. [root]272. See Moon.] One of the twelve portions into which the year is divided; the twelfth part of a year, corresponding nearly to the length of a synodic revolution of the moon, -- whence the name. In popular use, a period of four weeks is often called a month. Note: In the common law, a month is a lunar month, or twenty-eight days, unless otherwise expressed. --Blackstone. In the United States the rule of the common law is generally changed, and a month is declared to mean a calendar month. --Cooley's Blackstone. A month mind. (a) A strong or abnormal desire. [Obs.] --Shak. (b) A celebration made in remembrance of a deceased person a month after death. --Strype. Calendar months, the months as adjusted in the common or Gregorian calendar; April, June, September, and November, containing 30 days, and the rest 31, except February, which, in common years, has 28, and in leap years 29. Lunar month, the period of one revolution of the moon, particularly a synodical revolution; but several kinds are distinguished, as the synodical month, or period from one new moon to the next, in mean length 29 d. 12 h. 44 m. 2.87 s.; the nodical month, or time of revolution from one node to the same again, in length 27 d. 5 h. 5 m. 36 s.; the sidereal, or time of revolution from a star to the same again, equal to 27 d. 7 h. 43 m. 11.5 s.; the anomalistic, or time of revolution from perigee to perigee again, in length 27 d. 13 h. 18 m. 37.4 s.; and the tropical, or time of passing from any point of the ecliptic to the same again, equal to 27 d. 7 h. 43 m. 4.7 s. Solar month, the time in which the sun passes through one sign of the zodiac, in mean length 30 d. 10 h. 29 m. 4.1 s.