The phrase "serious hit" means something that has had a significant impact or has caused a lot of damage.
Sentences with «serious hit»
Two fields of planetary science took serious hits with today's announcement of the competition results. (sciencemag.org)
The more serious the hit and run accident, the bigger the risk is that an injured motorist's recovery will go unpaid. (davidchristensenlaw.com)
Schools and youth leagues are trying to get ahead of brain injuries with new impact sensors that alerts adults when a player has received a potentially serious hit. (today.com)