1. 箝闭：impacted fracture 嵌入骨折 | impaction 箝闭 | impedance 阻抗
2. 冲击：impact of unemployment 失业冲击 | impaction 冲击 | impaired 受损
3. 装紧：impactful 有效的 | impaction 装紧 | impactive 冲击的
4. 撞击：respirable dust 呼吸性粉尘 | impaction 撞击 | sedimentation 沉降
noun
1. a sharp collision produced by striking or dashing against something
Synonym: impingement
2. a disorder in which a tooth is so crowded in its socket that it cannot erupt normally
Synonym: impacted tooth
3. a disorder in which feces are impacted in the lower colon
4. the condition of being pressed closely together and firmly fixed