1. 紧缩：hike 加价,加息 | tightening 紧缩 | sluggish 不振的,不活跃的,停滞的

2. 扣紧：tight weld 密封焊缝 | tightening 扣紧 | tightening force 扣紧力

3. 使紧：tightener 紧带轮 | tightening 使紧 | tighteningbelt 拉紧皮带

4. 紧固：tight.strictseveresterndifficult 严竣 | tightening 紧固 | tightknit 组织严密的

noun

1. the act of making something tighter

e.g. the tightening of economic controls