To regrow means to grow back after being cut, damaged, or lost. When you cut your fingernails, they regrow over the following weeks. If you scrape your knee, new skin cells regrow to heal the wound. Gardeners know that when they harvest lettuce by cutting the leaves, the plant will regrow more leaves for another harvest.

Different living things have different abilities to regrow. Starfish can regrow lost arms. Lizards can regrow their tails if a predator grabs them. Trees regrow their leaves each spring after losing them in fall. Human hair regrows after a haircut, but if you lose a permanent tooth, it won't regrow, which is why we have to take good care of them!

Scientists study regrowth carefully because understanding how things regrow could help us heal injuries better. Some researchers are working to help human bodies regrow damaged tissues or organs, though this remains mostly in the future. For now, we can be grateful that our bodies already know how to regrow skin, hair, and nails naturally.