Why wooden splinters were lethal in battle

What are splinters, and what is splinter damage?

They are fragments thrown from the hull or other struck material; in wooden warships, cannon impacts could drive lethal showers of timber through the ship even when the ball did not penetrate cleanly.

A cannonball did not need to pass cleanly through a ship to harm its crew. An impact could shatter hull timbers and throw splinters through the interior, injuring people and damaging lines or equipment. The answer distinguishes this secondary damage from the direct path of the shot itself.