set off

definition: cause to burst with a violent release of energy
example: The kids set off rockets on the 4th of July.
speech part: verb
synonyms: blow up
definition: set in motion or cause to begin
example: Mixing Chlorine with Ammonia sets off a dangerous reaction.
speech part: verb
synonyms:
definition: direct attention to, as if by means of contrast
example:
speech part: verb
synonyms: bring out
definition: provoke or stir up
example: The use of tear gas set off the protesters.
speech part: verb
synonyms: instigate incite stir up
definition: put in motion or move to act
example:
speech part: verb
synonyms: trip
definition: leave where one is
example: I set off for London by foot with two quid and a biscuit.
speech part: verb
synonyms: start
definition: make up for
example:
speech part: verb
synonyms: offset

How set off is being used?