slow down vs slow up

slow down and slow up both are verbs.

Word	Noun	Adjective	Verb	Adverb
slow down	No	No	Yes	No
slow up	No	No	Yes	No

As verbs, slow down and slow up are synonyms defined as:

Other synonyms of slow down include decelerate, retard, slow.

As verbs, slow up is a hyponym of slow down; that is, slow up is a word with a more specific, narrower meaning than slow down:

Other hyponyms of slow down include slow, slow down, delay, detain, hold up.

As verbs, slow down and slow up are synonyms defined as:

Other synonyms of slow down include slack, slacken, slow.

As verbs, slow down and slow up are synonyms defined as:

Other synonyms of slow down include slow.

As verbs, slow up is a hypernym of slow down; that is, slow up is a word with a broader meaning than slow down:

Other hypernyms of slow down include decelerate, retard, slow, slow down.

slow down (verb)	slow up (verb)
become less tense, rest, or take one's ease	lose velocity; move more slowly
lose velocity; move more slowly	cause to proceed more slowly
become slow or slower	become slow or slower
reduce the speed of
cause to proceed more slowly