Open English Wordnet
Verbs
(v)restrain, confine, hold, constrainto close within bounds, or otherwise limit or deprive of free movement“This holds the local until the express passengers change trains”, “About a dozen animals were held inside the stockade”, “The illegal immigrants were held at a detention center”, “The terrorists held the journalists for ransom”
(v)stiffen, tighten, tighten up, constrainseverely restrict in scope or extent“tighten the rules”, “stiffen the regulations”