Trigger

Trigger:

Triggers are any sort of stimulus which can cause high levels of distress. They can also contribute to making a mental illness or similar symptom worse.

This is commonly in relation to trauma but can be used for anything including anxiety, OCD, and BPD. It can be experienced by singlets and systems. The word trigger has been as used as early as the late 1910s to describe war neurosis and shell shock.

Related Terms
Among systems, the term front trigger may also be used to refer to stimulus which can trigger switching.

"Trigger warnings" may be given in certain spaces for consideration of those who have triggers.

In the context of programming, triggers that activate programs are referred to as cues.