Trigger

detonatore

(event that initiates others, or incites a response)

grilletto

(finger-operated lever used to fire a gun)

impulso

(pulse in an electronic circuit that initiates some component)

innesco

(event that initiates others, or incites a response)

levetta

(similar device used to activate any mechanism)

accendere la miccia

(to initiate something)

attivare

(to initiate something)

attivare

((intransitive, especially electronics) to activate; to become active)

innescare

(to initiate something)

premere il grilletto

(to fire a weapon)

provocare

(to initiate something)

scatenare

(to initiate something)