rain cats and dogs, Informal. to rain very heavily or steadily: We canceled our picnic because it rained cats and dogs.

Origin of rain

before 900; (noun) Middle English rein; Old English regn, rēn, cognate with Dutch, German regen, Old Norse regn, Gothic rign; (v.) Middle English reinen, Old English regnian
Related formsrain·less, adjectiverain·less·ness, noun
Can be confusedrain reign rein

Synonyms for rain Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for rain cats and dogs



  1. precipitation from clouds in the form of drops of water, formed by the condensation of water vapour in the atmosphere
  2. a fall of rain; shower
  3. (in combination)a raindrop Related adjectives: hyetal, pluvious
a large quantity of anything falling rapidly or in quick successiona rain of abuse
rain or shine or come rain or shine
  1. regardless of the weather
  2. regardless of circumstances
right as rain British informal perfectly all right; perfectly fit


(intr ; with it as subject) to be the case that rain is falling
(often with it as subject) to fall or cause to fall like rainthe lid flew off and popcorn rained on everyone
(tr) to bestow in large measureto rain abuse on someone
rain cats and dogs informal to rain heavily; pour
rained off cancelled or postponed on account of rain
US and Canadian term: rained out
See also rains
Derived Formsrainless, adjective

Word Origin for rain

Old English regn; related to Old Frisian rein, Old High German regan, Gothic rign
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for rain cats and dogs



Old English regn "rain," from Proto-Germanic *regna- (cf. Old Saxon regan, Old Frisian rein, Middle Dutch reghen, Dutch regen, German regen, Old Norse regn, Gothic rign "rain"), with no certain cognates outside Germanic, unless it is from a presumed PIE *reg- "moist, wet," which may be the source of Latin rigare "to wet, moisten" (cf. irrigate). Rain dance is from 1867; rain date in listings for outdoor events is from 1948. To know enough to come in out of the rain (usually with a negative) is from 1590s. Rainshower is Old English renscur.



Old English regnian, usually contracted to rinan; see rain (n.), and cf. Old Norse rigna, Swedish regna, Danish regne, Old High German reganon, German regnen, Gothic rignjan. Related: Rained; raining. Transferred and figurative use of other things that fall as rain (blessings, tears, etc.) is recorded from c.1200.

To rain on (someone's) parade is attested from 1941. Phrase to rain cats and dogs is attested from 1738 (variation rain dogs and polecats is from 1650s), of unknown origin, despite intense speculation. One of the less likely suggestions is pets sliding off sod roofs when the sod got too wet during a rainstorm. (Ever see a dog react to a rainstorm by climbing up on an exposed roof?) Probably rather an extension of cats and dogs as proverbial for "strife, enmity" (1570s).

Online Etymology Dictionary, © 2010 Douglas Harper

Science definitions for rain cats and dogs



Water that condenses from water vapor in the atmosphere and falls to Earth as separate drops from clouds. Rain forms primarily in three ways: at weather fronts, when the water vapor in the warmer mass of air cools and condenses; along mountain ranges, when a warm mass of air is forced to rise over a mountain and its water vapor cools and condenses; and by convection in hot climates, when the water vapor in suddenly rising masses of warm air cools and condenses. See also hydrologic cycle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Idioms and Phrases with rain cats and dogs

rain cats and dogs

Also, rain buckets. Rain very heavily, as in It was raining cats and dogs so I couldn't walk to the store, or It's been raining buckets all day. The precise allusion in the first term, which dates from the mid-1600s, has been lost, but it probably refers to gutters overflowing with debris that included sewage, garbage, and dead animals. Richard Brome used a version of this idiom in his play The City Wit (c. 1652), where a character pretending a knowledge of Latin translates wholly by ear, “Regna bitque/and it shall rain, Dogmata Polla Sophon/dogs and polecats and so forth.” The variant presumably alludes to rain heavy enough to fill pails.


In addition to the idioms beginning with rain

  • rain cats and dogs
  • rain check
  • rain on one's parade
  • rain or shine
  • rain out
  • rainy day, a

also see:

  • come in out of the rain
  • it never rains but it pours
  • right as rain
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.