WordNet (r) 3.0 (2006):

set off
    v 1: put in motion or move to act; "trigger a reaction";
         "actuate the circuits" [syn: trip, actuate, trigger,
         activate, set off, spark off, spark, trigger off,
         touch off]
    2: leave; "The family took off for Florida" [syn: depart,
       part, start, start out, set forth, set off, set
       out, take off]
    3: direct attention to, as if by means of contrast; "This dress
       accentuates your nice figure!"; "I set off these words by
       brackets" [syn: bring out, set off]
    4: cause to burst with a violent release of energy; "We exploded
       the nuclear bomb" [syn: explode, detonate, blow up,
       set off]
    5: make up for; "His skills offset his opponent's superior
       strength" [syn: cancel, offset, set off]
    6: set in motion or cause to begin; "The guide set the tour off
       to a good start"
    7: provoke or stir up; "incite a riot"; "set off great unrest
       among the people" [syn: incite, instigate, set off,
       stir up]