tighten up

Từ điển WordNet v3.1 - WordNet Dictionary

verb

restrict (Freq. 1)
- Tighten the rules
- stiffen the regulations
• Syn:
stiffen, tighten, constrain
• Hypernyms:
restrict, restrain, trammel, limit, bound,
confine, throttle
• Verb Frames:
- Somebody ----s something