rain

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Water condensed from atmospheric vapor and falling in drops.
2. n. A fall of such water; a rainstorm.
3. n. The descent of such water.
4. n. Rainy weather.
5. n. A rainy season.
6. n. A heavy or abundant fall: a rain of fluffy cottonwood seeds; a rain of insults.
7. v. To fall in drops of water from the clouds.
8. v. To fall like rain: Praise rained down on the composer.
9. v. To release rain.
10. v. To send or pour down.
11. v. To give abundantly; shower: rain gifts; rain curses upon their heads.
12. rain out To force the cancellation or postponement of (an outdoor event) because of rain. Used in passive constructions: The ball game was rained out.
13. idiom. rain cats and dogs Informal To rain very heavily.

Century Dictionary and Cyclopedia

1. n. The descent of water in drops through the atmosphere, or the water thus falling. In general, clouds constitute the reservoir from which rain descends, but the fall of rain in very small quantities from a cloudless sky is occasionally observed. The aqueous vapor of the atmosphere, which condenses into cloud, and falls as rain, is derived from the evaporation of water, partly from land, but chiefly from the vast expanse of the ocean. At a given temperature, only a certain amount of aqueous vapor can be contained in a given volume, and when this amount is present the air is said to be saturated. If the air is then cooled below this temperature, a part of the vapor will be condensed into small drops, which, when suspended in the atmosphere, coustitute clonds. Under continued cooling and condensation, the number and size of the drops increase until they begin to descend by their own weight. The largest of these, falling fastest, unite with smaller ones that they overtake, and thus drops of rain are formed whose size depends on the thickness and density of the cloud and on the distribution of electrical stress therein. Sometimes the rate of condensation is so great that the water appears to fall in sheets rather than in drops, and then the storm is popularly called a cloud-burst. It is now generally held that dynamic cooling (that is, the cooling of air by expansion, when raised in altitude, and thereby brought under diminished pressure), if not the sole cause of rain, is the only cause of any importance, and that other causes popularly appealed to—such as the intermingling of warm and cold air, contact with cold mountain-slopes, etc.—are either inoperative or relatively insignificant. The requisite ascent of air may be occasioned either by convection currents, a cyclonic circulation, or the upward deflection of horizontal currents by hills or mountains; and rain may be classified as convectivc, cyclonic, or orographic, according as the first, second, or third of these methods is brought into operation to produce it. The productiveness of the soil and the maintenance of life in most parts of the earth depend largely upon an adequate fall of rain. In some regions it is more or less evenly distributed throughout the year, in others it is confined to a part of the year (the rainy season), and in others still it is entirely absent, or too slight for need, according to variation of local atmospheric conditions. In a ship's log-book abbreviated r.
2. n. Figuratively— A fall of any substance through the atmosphere in the manner of rain, as of blossoms or of the pyrotechnic stars from rockets and other fireworks. Blood-rain is a fall of fragments of red algæ or the like, raised in large quantities by the wind and afterward precipitated. Sulphur-rain or yellow rain is a similar precipitation of the pollen of fir-trees, etc.
3. n. A shower, downpour, or abundant outpouring of anything.
4. n. Synonyms Rain, Haze, Fog, Mist, Cloud. A cloud resting upon the earth is called mist or fog. In mist the globules are very fine, but are separately distinguishable, and have a visible motion. In fog the particles are separately indistinguishable, and there is no perceptible motion. A dry fog is composed largely of dust-particles on which the condensed vapor is too slight to occasion any sense of moisture. Haze differs from fog and cloud in the greater microscopic minuteness of its particles. It is visible only as a want of transparency of the atmosphere, and in general exhibits neither form, boundary, nor locus. Thus, among haze, fog, mist, and rain, the size of the constituent particles or globules is a discriminating characteristic, though frequently cloud merges into fog or mist, and mist into rain, by insensible gradations.
5. To fall in drops through the air, as water: generally used impersonally.
6. To fall or drop like rain; as, tears rained from their eyes.
7. To pour or shower down, like rain from the clouds; pour or send down abundantly.
8. n. A ridge.
9. n. A furrow.
10. n. An obsolete spelling of rein.

Wiktionary

1. n. Condensed water falling from a cloud.
2. n. figuratively Any matter moving or falling, usually through air, and especially if liquid or otherwise figuratively identifiable with raindrops.
3. n. figuratively An instance of particles or larger pieces of matter moving or falling through air.
4. v. impersonal To have rain fall from the sky.
5. v. intransitive To fall in large quantities.
6. v. transitive To issue (something) in large quantities.

GNU Webster's 1913

1. obsolete Reign.
2. n. Water falling in drops from the clouds; the descent of water from the clouds in drops.
3. v. To fall in drops from the clouds, as water; -- used mostly with it for a nominative.
4. v. To fall or drop like water from the clouds.
5. v. To pour or shower down from above, like rain from the clouds.
6. v. To bestow in a profuse or abundant manner.

WordNet 3.0

1. n. water falling in drops from vapor condensed in the atmosphere
2. n. anything happening rapidly or in quick successive
3. n. drops of fresh water that fall as precipitation from clouds
4. v. precipitate as rain