sea

noun

• A large body of salt water.
• A lake, especially if large or if salty or brackish.

  "The Caspian Sea, the Sea of Galilee, the Salton Sea, etc."

• The swell of the sea; a single wave; billow.
• (in combination) Living or used in or on the sea; of, near, or like the sea.

  "Seaman, sea gauge, sea monster, sea horse, sea level, seaworthy, seaport, seaboard, etc."

• Anything resembling the vastness or turbulence of the sea.
• A constant flux of gluons splitting into quarks, which annihilate to produce further gluons.
• A large, dark plain of rock; a mare.

  "The Apollo 11 mission landed in the Sea of Tranquility."

• A very large lake of liquid hydrocarbon.