[syn: trip, actuate, trigger, activate, set off, spark off, spark, trigger off, touch off]
2.  release or pull the trigger on; 
- Example: "Trigger a gun"
The Collaborative International Dictionary of English v.0.48:
Trigger \Trig"ger\, n. [For older tricker, from D. trekker, fr.
   trekken to draw, pull. See Trick, n.]
   1. A catch to hold the wheel of a carriage on a declivity.
      [1913 Webster]
   2. (Mech.) A piece, as a lever, which is connected with a
      catch or detent as a means of releasing it; especially
      (Firearms), the part of a lock which is moved by the
      finger to release the cock and discharge the piece.
      [1913 Webster]
   Trigger fish (Zool.), a large plectognath fish (Balistes
      Carolinensis or Balistes capriscus) common on the
      southern coast of the United States, and valued as a food
      fish in some localities. Its rough skin is used for
      scouring and polishing in the place of sandpaper. Called
      also leather jacket, and turbot.
      [1913 Webster]
WordNet (r) 3.0 (2006):
trigger
    n 1: lever that activates the firing mechanism of a gun [syn:
         gun trigger, trigger]
    2: a device that activates or releases or causes something to
       happen
    3: an act that sets in motion some course of events [syn:
       trigger, induction, initiation]
    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: release or pull the trigger on; "Trigger a gun"
The Free On-line Dictionary of Computing (30 December 2018):
trigger
    An action causing the automatic invocation of a
   procedure, for instance to preserve referential integrity.
   A triggers goes into effect when a user attempts to modify
   data with an insert, delete, or update command.  A trigger can
   instruct the system to take any number of actions when a
   specified change is attempted.  By preventing incorrect,
   unauthorized, or inconsistent changes to data, triggers help
   maintain the integrity of the database.
   [Sybase SQL Server Release 10.0 Transact-SQL User's Guide].
   (1995-02-22)