concussion

1 a forceful coming together of two things the concussion of the airliner slamming into the skyscraper was felt for several blocks in all directions Synonyms bump, collision, impact, crash, impingement, jar, jolt, jounce, kick, shock, slam, smash, strike, wallopRelated Words blow, buffet, hit, knock, punch, rap, slap, thump; bashing, battering, bludgeoning, clobbering, hammering, lambasting, licking, pounding, pummeling (also pummelling), thrashing; contact, encounter, meeting, touch

2 the violent coming together of two bodies into destructive contact the theory that such a concussion, by a giant asteroid or comet millions of years ago, led to the extinction of the dinosaurs Synonyms collision, crash, crack-up, smash, smashup, wreckRelated Words accident, pileup; demolishment, destruction, ruin