To chirp means to make the short, high-pitched sound that small birds and insects make. When a robin greets the morning or a cricket calls in the evening grass, that quick, bright sound is a chirp. The sound is usually repetitive: chirp, chirp, chirp. Baby birds chirp loudly in their nest when they're hungry, and sparrows chirp to each other from telephone wires.

The word captures something about the sound itself: quick, light, and slightly musical. You might hear someone say the birds were chirping cheerfully outside their window, or that crickets chirped all night long in the summer.

As a noun, a chirp is that sound itself: a bird’s chirp, a cricket’s chirp, or a whole chorus of chirps.

People sometimes use chirp playfully to describe a person speaking in a bright, cheerful way, especially with a higher-pitched voice. If your friend greets you with an enthusiastic “Good morning!” in a singsongy voice, you might say she chirped her greeting. The word suggests happiness and energy, like the sound of birds welcoming a new day.