VT to fire a weapon.
VT to spark a response, especially a negative emotional response, in (someone).
To trigger neoblast proliferation and differentation, two days head and tail regenerating animals were used for the preparation of the libraries.
Meaning of trigger for the defined word.
Grammatically, this word "trigger" is a noun, more specifically, a countable noun. It's also a verb, more specifically, a transitive verb.