tighten

(verb) make tight or tighter. Synonyms: fasten. Example: "Tighten the wire."

(verb) become tight or tighter. Example: "The rope tightened."

(verb) restrict. Synonyms: stiffen, tighten up, constrain. Examples: "Tighten the rules." "Stiffen the regulations."

(verb) narrow or limit. Synonyms: reduce. Example: "Reduce the influx of foreigners."