rain

Concise Oxford English Dictionary © 2008 Oxford University Press:
rain/reɪn/

▶noun

• 1 the condensed moisture of the atmosphere falling visibly in separate drops.

  ■ (rains) falls of rain.

• 2 a large quantity of things falling or descending: a rain of blows.

▶verb

• 1 (it rains, it is raining, etc.) rain falls.

• 2 (be rained off or N. Amer. out) (of an event) be cancelled or interrupted because of rain.

• 3 fall or cause to fall in large quantities: bombs rained down.

– phrases
be as right as rain be perfectly fit and well.
rain cats and dogs rain heavily.

– derivatives
rainless adjective.

– origin OE regn (n.), regnian (v.), of Gmc origin.