slow down

verb

1. To decelerate.

   “When approaching a bend in the road, slow down, and speed up after leaving it.”

   “Crossing stations on single lines are laid out so that one line has a straight run through, and is signalled in each direction, avoiding the need to slow down to take the turnout into the loop.”

2. To reduce the velocity, speed, or tempo of something.

   “With a comfortable lead, the football team slowed down the tempo of the game.”

   “A "passenger/goods" cock is provided in each cab, by which, when placed in the "goods" position, the normal proportional brake application is slowed down. This is for use when hauling an unbraked or partially braked train, and prevents the unbraked stock from running into the locomotive or braked portion of the train with violence.”

3. To become less intense, enthusiastic, etc., usually with a positive connotation, implying that one is stripped of exaggerated or unnecessary eagerness.

   “Whoa, slow down there, bucko. Everyone will get a chance. Be patient.”