Something seen, heard, felt, etc., which "triggers" a response, urge, memory, or emotion, etc., such as turning the key in the car might "trigger" a smoker to light up a cigarette.
Substances or situations that can cause inflammation or swelling in the airway. Some common triggers are cigarette smoke, animal dander, dust mites and viral infections such as a cold.
A pre-programmed signal, something seen (like a color) or heard (word, phrase, or sound) or felt, that "triggers" a specific response. Unconscious--The repressed psychological material held within the subconscious mind and any other material held within the subconscious of which we are unaware.