exothermic

Imagine building a campfire. As the wood burns, it feels warm, right? That warmth is heat moving out into the air around it. That is what this word describes. The prefix "exo-" means "out," and "-thermic" relates to heat, so the idea is literally "heat out." It is used for a process that gives off heat to its surroundings. This is not just about fire; many chemical reactions, like burning fuel, some hand warmers, or the way cement sets, fit this idea. You'll often hear it in science class when people talk about chemistry or physics.

The word "exothermic" describes a process that releases heat to its surroundings. It is most commonly used in science, especially in chemistry and physics, for reactions or changes that send heat outward rather than taking heat in.

Think about it like this: some things require heat from outside to happen, like melting ice. An exothermic process goes the other way: it gives off heat, often making the area around it warmer. A classic example is combustion, or burning. When wood burns, stored chemical energy is released, and some of that energy comes out as heat and light.

However, it is not limited to burning. Many chemical reactions are exothermic, including neutralization reactions and the oxidation used in many hand warmers. Some setting and curing processes also release heat; for instance, cement can grow quite warm as it hardens. In biology, cellular respiration, the process by which our bodies get usable energy from food, involves steps that release heat as well.

Scientists also use the term in a precise way when measuring heat flow. In chemistry, a negative enthalpy change is a sign that a reaction is exothermic. So when a reaction or process gives off warmth to the world around it, this is the word that explains what is happening.