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English definition of “set sth off”

set sth off

phrasal verb with set     /set/ verb (present participle setting, past tense and past participle set)
to make something begin or happen , especially a loud noise or a lot of activity : He's always burning the toast and setting off the smoke alarm .Causing things to happen
(Definition of set sth off from the Cambridge Learner's Dictionary © Cambridge University Press)

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