To indicate the threshold or level above which something will become unacceptable or will provoke a response; to create a boundary and imply or declare that its crossing will provoke a (negative) response.
To lay down a challenge; to provide a test of commitment (often one which carries a high risk) to a cause.
To create a real or artificial boundary or distinction between (two places, people or things).
To spark a response, especially a negative emotional response, in (someone).
To fire a weapon.
To initiate something.
To activate; to become active.
An electronic transducer allowing a drum, cymbal, etc. to control an electronic drum unit or similar device.
An event, experience or other stimulus that initiates a traumatic memory or a strong reaction in a person.
An SQL procedure that may be initiated when a record is inserted, updated or deleted; typically used to maintain referential integrity.
A concept or image that upsets somebody by sparking a negative emotional response.
A similar device used to activate any mechanism.
An event that initiates others, or incites a response.
A pulse in an electronic circuit that initiates some component.
A text string that, when received by a player, will cause the player to execute a certain command.
A device that manually lengthens (or sometimes shortens) the slide or tubing of a brass instrument, allowing the pitch range to be altered while playing.
A finger-operated lever used to fire a gun.