Source : Webster's Revised Unabridged Dictionary (1913)

Welter \Wel"ter\, v. i. [imp. & p. p. {Weltered}; p. pr. & vb.
   n. {Weltering}.] [Freq. of OE. walten to roll over, AS.
   wealtan; akin to LG. weltern, G. walzen to roll, to waltz,
   sich w["a]lzen to welter, OHG. walzan to roll, Icel. velta,
   Dan. v[ae]lte, Sw. v["a]ltra, v["a]lta; cf. Goth. waltjan;
   probably akin to E. wallow, well, v. i. ????. See {Well}, v.
   i., and cf. {Waltz}.]
   1. To roll, as the body of an animal; to tumble about,
      especially in anything foul or defiling; to wallow.

            When we welter in pleasures and idleness, then we
            eat and drink with drunkards.         --Latimer.

            These wizards welter in wealth's waves. --Spenser.

            He must not float upon his watery bier Unwept, and
            welter to the parching wind, Without the meed of
            some melodious tear.                  --Milton.

            The priests at the altar . . . weltering in their
            blood.                                --Landor.

   2. To rise and fall, as waves; to tumble over, as billows.
      ``The weltering waves.'' --Milton.

            Waves that, hardly weltering, die away.
                                                  --Wordsworth.

            Through this blindly weltering sea.   --Trench.

Welter \Wel"ter\, n.
   1. That in which any person or thing welters, or wallows;
      filth; mire; slough.

            The foul welter of our so-called religious or other
            controversies.                        --Carlyle.

   2. A rising or falling, as of waves; as, the welter of the
      billows; the welter of a tempest.

Welter \Wel"ter\, v. t. [Cf. {Wilt}, v. i.]
   To wither; to wilt. [R.]

         Weltered hearts and blighted . . . memories. --I.
                                                  Taylor.

Welter \Wel"ter\, a. (Horse Racing)
   Of, pertaining to, or designating, the most heavily weighted
   race in a meeting; as, a welter race; the welter stakes.

Source : WordNet®

welter
     n : a confused multitude of things [syn: {clutter}, {jumble}, {muddle},
          {mare's nest}, {smother}]
     v 1: toss, roll, or rise and fall in an uncontrolled way; "The
          shipwrecked survivors weltered in the sea for hours"
     2: roll around, "pigs were wallowing in the mud" [syn: {wallow}]
     3: be immersed in; "welter in work"