slow down is a verb meaning "lose velocity; move more slowly". It carries 5 recorded senses.
cause to proceed more slowly
“The illness slowed him down”
reduce the speed of
“He slowed down the car”
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”
Definitions, synonyms and semantic relations for slow down come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.