Meaning of TRIGGER in English
1》 a device that releases a spring or catch and so sets off a mechanism, especially in order to fire a gun.
2》 an event that causes something to happen.
1》 cause (a device) to function.
2》 (also ~ something off ) cause to happen or exist.
C17: from dialect tricker , from Du. trekker , from trekken 'to pull'.
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004