Webster's Revised Unabridged Dictionary · 1913

Sea

Sea (sē) , noun

[Old English see, Anglo-Saxon sa; akin to Dutch zee, Old Saxon & Old High German sēo, German see, OFries. se, Danish so, Swedish sjo, Icelandic saer, Gothic saiws, and perhaps to Latin saevus fierce, savage. r151a.]

1.
One of the larger bodies of salt water, less than an ocean, found on the earth's surface; a body of salt water of second rank, generally forming part of, or connecting with, an ocean or a larger sea; as, the Mediterranean Sea; the Sea of Marmora; the North Sea; the Carribean Sea.
2.
An inland body of water, esp. if large or if salt or brackish; as, the Caspian Sea; the Sea of Aral; sometimes, a small fresh-water lake; as, the Sea of Galilee.
3.
The ocean; the whole body of the salt water which covers a large part of the globe.
I marvel how the fishes live in the sea. — Shakespeare
Ambiguous between sea and land The river horse and scaly crocodile. — Milton
4.
The swell of the ocean or other body of water in a high wind; motion or agitation of the water's surface; also, a single wave; a billow; as, there was a high sea after the storm; the vessel shipped a sea.
5.
(Jewish Antiquities) A great brazen laver in the temple at Jerusalem; -- so called from its size.
He made a molten sea of ten cubits from brim to brim, round in compass, and five cubits the height thereof. — 2 Chron. iv. 2
6.
Figuratively: Anything resembling the sea in vastness; as, a sea of glory. — Shakespeare
All the space... was one sea of heads. — Macaulay

Sea is often used in the composition of words of obvious signification; as, sea-bathed, sea-beaten, sea-bound, sea-bred, sea-circled, sealike, sea-nursed, sea-tossed, sea-walled, sea-worn, and the like. It is also used either adjectively or in combination with substantives; as, sea bird, sea-bird, or seabird, sea acorn, or sea-acorn.

Collocations (8)
At sea , upon the ocean; away from land; figuratively, without landmarks for guidance; lost; at the mercy of circumstances. To say the old man was at sea would be too feeble an expression. — G. W. Cable
At full sea , at the height of flood tide; hence, at the height. But now God's mercy was at full sea. — Jer. Taylor
Beyond seas or Beyond the sea or Beyond the seas (Law) , out of the state, territory, realm, or country. — Wharton
Half seas over , half drunk. [Colloquial] — Spectator
Heavy sea , a sea in which the waves run high.
Long sea , a sea characterized by the uniform and steady motion of long and extensive waves.
Short sea , a sea in which the waves are short, broken, and irregular, so as to produce a tumbling or jerking motion.
To go to sea , to adopt the calling or occupation of a sailor.