A sound is a noise, something you can hear if you're in the right spot and it's loud enough. A doorbell, a fire alarm, a cat's meow, or your brother's snoring — they’re all sounds.
Long Island Sound is another kind of sound — it’s a branch of the Atlantic Ocean that runs between Connecticut and Long Island, New York. When you don’t know a word, you might sound out the syllables — say them aloud — to figure out the pronunciation. Sound can also mean "solid or good." Sound advice is good advice. Sound investments are secure. When you have a sound sleep, it's restful and uninterrupted — at least until your alarm sounds.