sea \sea\ s=e, n. oe. see, as. s=ae; akin to d. zee, os.
    ohg. s=eo, g. see, ofries. se, dan. s"o, sw. sj"o,
   icel. saer, goth. saiws, and perhaps to l. saevus fierce,
   savage. root151a.
   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.
      1913 webster

   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.
      1913 webster

   3. the ocean; the whole body of the salt water which covers a
      large part of the globe.
      1913 webster

            i marvel how the fishes live in the sea. --shak.
      1913 webster

            ambiguous between sea and land
            the river horse and scaly crocodile.  --milton.
      1913 webster

   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.
      1913 webster

   5. jewish antiq. a great brazen laver in the temple at
      jerusalem; -- so called from its size.
      1913 webster

            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.
      1913 webster

   6. fig.: anything resembling the sea in vastness; as, a sea
      of glory. --shak.
      1913 webster

            all the space . . . was one sea of heads.
                                                  --macaulay.
      1913 webster

   note: 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.
         1913 webster

   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. colloq. --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.
      1913 webster
see also:
at sea at full sea beyond seas beyond the sea beyond the seas half seas over 
heavy sea long sea short sea to go to sea 

at sea
     adj 1: perplexed by many conflicting situations or statements;
            filled with bewilderment; "obviously bemused by his
            questions"; "bewildered and confused"; "a cloudy and
            confounded philosopher"; "just a mixed-up kid"; "she
            felt lost on the first day of school" syn: baffled,
             befuddled, bemused, bewildered, confounded, confused,
             lost, mazed, mixed-up
     2: traveling by boat or ship syn: at seap, sailing
see also:
baffled befuddled bemused bewildered confounded confused 
lost mazed mixed-up at seap sailing 

45 moby thesaurus words for "at sea":
   abashed, abroad, adrift, afloat, astray, bewildered, bothered,
   by sea, by water, clueless, confused, discomposed, disconcerted,
   dismayed, disoriented, distracted, distraught, disturbed,
   embarrassed, guessing, homeward bound, in a fix, in a maze,
   in a pickle, in a scrape, in a stew, in blue water, in soundings,
   lost, making way, mazed, off soundings, off the course,
   off the heading, off the track, perturbed, put-out, turned around,
   under bare poles, under sail, under way, upset, with sails spread,
   with way on, without a clue