If something slows down or is if something slows it down, it starts to move or happen more slowly. The car slowed down as they passed Customs There is no cure for the disease, although drugs can slow down its rate of development Damage to the turbine slowed the work down. = slow up speed up
If someone slows down or if something slows them down, they become less active. You will need to slow down for a while He was still taking some medication which slowed him down. see also slowdown