Meaning of “be rained off” - Learner’s Dictionary

be rained off

UK (US be rained out) phrasal verb with rain uk us /reɪn/ verb

If a sport or outside activity is rained off, it cannot start or continue because it is raining:

Most of today's matches were rained off.

(Definition of “be rained off” from the Cambridge Learner’s Dictionary © Cambridge University Press)