Main Entry: ⁵sound

Function: noun

Etymology: Middle English, from Old English sund swimming, sea & Old Norse sund swimming, strait; akin to Old English swimman to swim

Date: 14th century

1 a : a long broad inlet of the ocean generally parallel to the coast b : a long passage of water connecting two larger bodies (as a sea with the ocean) or separating a mainland and an island
2 : the air bladder of a fish