Noisy means making a lot of loud sound, or filled with loud sounds. A noisy classroom buzzes with conversations, shuffling papers, and scraping chairs. A noisy construction site clangs with hammers, roars with machinery, and rumbles with trucks. When your little brother plays noisily with his toys, he's crashing them together and making sound effects at top volume.

The word suggests a chaotic, distracting quality of sound. A single trumpet playing beautifully might be loud, but a room full of people all talking at once is noisy because the sounds jumble together without order or pattern. A thunderstorm is loud, but a bunch of pots and pans clattering onto a kitchen floor is noisy because the sounds clash and compete for attention.

People use noisy beyond just sound, too. Scientists talk about noisy data when their measurements include random variations that make patterns hard to see, like trying to hear a whisper in a crowded cafeteria. In this sense, noisy means cluttered with unwanted information.

The opposite of noisy is quiet or calm. After a noisy day at school, coming home to a quiet house can feel wonderfully peaceful.