To ignite means to catch fire or cause something to catch fire. When you ignite a candle, you light the wick and it starts burning. A match ignites when you strike it against the matchbox, creating a small flame. Lightning can ignite a dry forest, starting a wildfire that spreads quickly.

The word is closely related to the word ignition. When you turn the key in a car, the ignition system ignites the fuel inside the engine, creating the controlled explosions that make the car run.

Beyond literal fire, ignite describes anything that sparks something into action or sets it off dramatically. A great teacher might ignite your curiosity about science, making you suddenly want to learn everything about chemistry or astronomy. A rousing speech can ignite enthusiasm in a crowd. When someone says an incident ignited a controversy, they mean it started an intense argument or debate that spread quickly, much like fire itself.

The word suggests a sudden beginning and rapid growth. A small spark ignites kindling, which ignites larger logs, which can ignite an entire campfire. That same pattern applies whether you're talking about actual flames or the spark of an idea that ignites change.