verb
1.
Synonyms: delay 1, bog (down), decelerate, detain, embog, hang up, mire, retard, set back, slow (up or down)
Idioms: keep back
Antonyms: quicken
2.
Synonyms: abate 4, die (down or away), ease off, ebb, fall, let up, moderate, relent, subside, wane
3.
Synonyms: loose 5, ease, ease off, lax, loosen, relax, slack, untighten
Antonyms: tighten