Sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.
The word "sound" can also mean:
1. To seem or appear in a particular way ("That sounds great!")
2. Healthy or in good condition ("sound body")
3. Thorough or complete ("sound sleep")
4. A narrow stretch of water ("Long Island Sound")
5. To measure the depth of water ("sound the depth")