From Longman Dictionary of Contemporary Englishslow down phrasal verb1SLOWto become slower or to make something slowerGrowth in sales has slowed down.slow somebody/something ↔ downThe ice on the road slowed us down.2BUSY/HAVE A LOT TO DO#to become less active or busy than you usually areIt is important to slow down, rest, and eat sensibly. →slow→ See Verb table
Examples from the Corpus
slow down• We could have been here hours ago, but the rainslowed us down.• Everyone's always rushing around trying to get things done - we all need to slow down and take it easy.• Slow down! You're driving too fast!