concussion

Từ điển American Heritage Dictionary 4th

con·cus·sion (kən-kŭshʹən)n.
1. A violent jarring; a shock. See Synonyms at collision.
2. An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function. [Middle English concussioun, bruise, contusion, from Latin concussiō, concussiōn-, concussion, from concussus, past participle of concutere, to strike together. See concuss.] con·cusʹsive (-kŭsʹĭv) adj.con·cusʹsive·ly adv.