Delay, retard, reduce speed, as in She slowed down the sled by dragging her foot, or Slow down, Bill; you're driving much too fast. [First half of 1800s] Also see slow up.
Become less active or vigorous, as in Now that I'm in my seventies I find I've slowed down quite a bit. [Second half of 1800s]
Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.