/ˈtaɪtn ||; ˈtaɪtṇ/verb [I,T] tighten (sth) (up) to become or to make sth tight or tighter （使）变紧: His grip on her arm tightened. 他把她的手臂抓得更紧。He tightened the screws as far as they would go. 他尽量把螺丝拧紧。 tighten your belt to spend less money because you have less than usual available 勒紧裤带；省吃俭用 tighten up (on) sth to cause sth to become stricter 使更严格: to tighten up security/a law 加强安全措施；使一项法律更严格