[mass noun]temporary unconsciousness caused by a blow on the head. The term is also used loosely of the after-effects such as confusion or temporary incapacity (头部被击导致的)暂时知觉丧失;脑震荡
a violent shock as from a heavy blow 猛击;剧烈震动;震荡 the ground shuddered with the concussion of the blast. 地面由于爆炸的冲击而震动。
语源
late Middle English: from Latin concussio(n-), from the verb concutere 'dash together, shake' (see concuss)