1. To slow one's vehicle down by or as by pulling back the throttle that controls the amount of fuel delivered to an engine. A noun or pronoun can be used between "throttle" and "back." Now, you'll want to throttle back as we approach the harbor. Investigators at the crash scene believe the driver failed to throttle the car back while taking the turn.

2. To slow down one's or something's activity or rate. A noun or pronoun can be used between "throttle" and "back." We're beginning to throttle production back in response to the stagnating economy. After a month of searching, police are throttling back their efforts to find the missing teenager.