rain

1 rain /ˈreɪn/ noun
plural rains
1 rain
/ˈreɪn/
noun
plural rains
Britannica Dictionary definition of RAIN
1 
: water that falls in drops from clouds in the sky
[noncount]
[count]
— see also acid rain
2 
[noncount] : weather in which there is a lot of rain : rainy weather
3 
rains [plural] : large amounts of rain that fall at a particular time of year
4 
[singular] : a large amount of something falling from above

(as) right as rain

— see 1right

rain or shine

or come rain, come shine or come rain or come shine
— used to say that something will happen even if it rains — sometimes used figuratively
2 rain /ˈreɪn/ verb
rains; rained; raining
2 rain
/ˈreɪn/
verb
rains; rained; raining
Britannica Dictionary definition of RAIN
1 
[no object] — used with it to say that rain is falling
2 
always followed by an adverb or preposition, [no object] : to fall from above in large amounts
3 
[+ object] : to cause (something) to fall in large amounts

be rained out

(US) or British be rained off
: to be canceled because of rain

rain cats and dogs

informal
: to rain very hard

rain on someone's parade

US, informal
: to spoil someone's pleasure

when it rains, it pours

(US) informal or chiefly British it never rains but it pours
— used to say that when something bad happens other bad things usually happen at the same time