sea
n. C / Un. a large area of salt water, smaller than an ocean. You might go to the sea for your holiday to swim or relax on the beach.
n. a large body of salt water, wholly or partly enclosed by land. It can also refer more generally to the ocean.
The ship sails on the sea.
We spent the afternoon swimming in the warm sea.
The old lighthouse stood as a lonely sentinel against the fury of the winter sea.
Inherited from Middle English see, from Old English sǣ, from Proto-West Germanic saiwi (“body of water”), from Proto-Germanic saiwiz, itself either: Derived from Proto-Indo-European sh₂ey-wo- (“to be fierce, afflict”). Related to Latin saevus (“wild, fierce”), Tocharian B saiwe (“itch”), and Latvian sievs, sīvs (“sharp, biting”). More at sore. Derived from Proto-Germanic sīhwaną (“to percolate, filter”), from Proto-Indo-European *seykʷ-. Cognates Cognate with Yola zea, zee (“sea”), North Frisian See, sia, siie (“sea; lake”), Saterland Frisian See, Säi (“sea”), West Frisian see (“sea”), Cimbrian, Mòcheno sea (“lake”), Dutch zee (“sea”), German, German Low German See (“sea”), Limburgish Sië, zieë (“sea, ocean; lake”), Luxembourgish Séi (“lake”), West Flemish zji (“sea; seaside”), Danish sø (“sea; lake”), Faroese sjógvur (“sea; big wave”), Icelandic sjár, sjór, sær (“sea”), Norwegian Bokmål, Norwegian Nynorsk sjø (“sea, ocean; lake”), Swedish sjö (“sea; lake; big wave”), Gothic 𐍃𐌰𐌹𐍅𐍃 (saiws, “lake, sea; marshland”).
Typically used with the definite article 'the' when referring to the ocean in a general sense. It is countable when referring to specific, named bodies of water (e.g., 'the North Sea').
I was swimming at the sea.I was swimming in the sea.Use 'in the sea' for being in the water. The phrase 'at sea' means to be on a ship on a voyage, far from land.