A Sound

Etymology 3

from Proto-Indo-European *swem- (“swimming; sea”).

1. (geography) A long narrow inlet, or a strait between the mainland and an island; also, a strait connecting two seas, or connecting a sea or lake with the ocean.
2. The air bladder of a fish.
3. (medicine) A long, thin probe for sounding or dilating body cavities or canals such as the urethra; a sonde.