Ingrown describes something that grows inward into surrounding tissue instead of outward the way it usually does. The most common example is an ingrown toenail, which happens when the edge of a toenail curves and digs into the skin beside it instead of growing straight out. This causes pain, redness, and sometimes infection.

Ingrown toenails often develop from wearing shoes that are too tight, cutting toenails incorrectly (cutting them too short or rounding the edges), or injuring the toe. While anyone can get an ingrown toenail, they're especially common in teenagers whose feet are growing quickly.

The word can also describe ingrown hairs, which happen when a hair curls back and grows into the skin instead of rising up through it. This creates a small, sometimes painful bump.

When doctors or parents talk about something being ingrown, they're describing a situation where the body's normal growth pattern has gone wrong. The fix usually involves careful trimming, keeping the area clean, and sometimes seeing a doctor if it's infected.