Shook is the past tense of shake. When something shook, it moved quickly back and forth or up and down. The earthquake shook the building. The dog shook water off its fur after jumping in the lake. A teacher might have shaken her head in disappointment when students weren't paying attention.

Shook can also describe feeling rattled or upset by something unexpected. When you're shook, something surprised or disturbed you enough to throw off your normal confidence. You might feel shook after nearly falling off your bike, or after discovering you studied the wrong chapter before a test. A scary movie might leave you feeling shook for hours afterward.

In this second sense, people sometimes say they're “shaken up” by an experience, using the related word shaken. Being shook means something got under your skin and left you feeling unsettled or thrown off balance, the way a physical shake can leave objects wobbling.