1. A swelling, normal or abnormal: "Intumescence is the swelling of certain substances when they are heated and intumescences are often accompanied by the release of water."
2. A swollen organ or body part: "Intumescence consists of the swelling up with blood or other fluids; such as, with congestion or spinal enlargements."
3. In chemistry, the swelling of certain substances when heated, often accompanied by the escape of water vapor.