trigger
n. countablen. something that causes a sudden reaction or makes a specific event happen. In psychology, it is often a memory or situation that makes someone feel strong, difficult emotions.
n. an event, situation, or stimulus that initiates a specific process or reaction. In psychological contexts, it refers to a sensory or situational input that causes a person to recall a traumatic experience or experience a sudden emotional shift.
The smell of smoke was a trigger for his anxiety.
Loud noises can be a trigger for veterans who suffer from post-traumatic stress disorder.
Economists identified the sudden collapse of the housing market as the primary trigger for the subsequent global recession, though underlying structural weaknesses had been present for years.
Originally tricker, from Dutch trekker (“pull”, noun, as in drawer-pull, bell-pull), from Dutch trekken (“to drag, draw, pull”).
Often used with the preposition 'for' to indicate the resulting action or state.