From WordNet (r) 3.0 (2006):
slow down
v 1: lose velocity; move more slowly; "The car decelerated"
[syn: decelerate, slow, slow down, slow up,
retard] [ant: accelerate, quicken, speed, speed
up]
2: become slow or slower; "Production slowed" [syn: slow,
slow down, slow up, slack, slacken]
3: cause to proceed more slowly; "The illness slowed him down"
[syn: slow, slow down, slow up]
4: reduce the speed of; "He slowed down the car" [syn:
decelerate, slow down] [ant: accelerate, speed,
speed up]
5: become less tense, rest, or take one's ease; "He relaxed in
the hot tub"; "Let's all relax after a hard day's work" [syn:
relax, loosen up, unbend, unwind, decompress, slow
down] [ant: tense, tense up]