The Collaborative International Dictionary of English v.0.48:

Lump \Lump\ (l[u^]mp), n. [Cf. OD. lompe piece, mass. Cf.
   Lunch.]
   1. A small mass of matter of irregular shape; an irregular or
      shapeless mass; as, a lump of coal; a lump of iron ore. "
      A lump of cheese." --Piers Plowman. " This lump of clay."
      --Shak.
      [1913 Webster]

   2. A mass or aggregation of things.
      [1913 Webster]

   3. (Firearms) A projection beneath the breech end of a gun
      barrel.
      [1913 Webster]

   In the lump,

   In a lump, the whole together; in gross.
      [1913 Webster]

            They may buy them in the lump.        --Addison.

   Lump coal, coal in large lumps; -- the largest size brought
      from the mine.

   Lump sum,
      (a) a gross sum without a specification of items; as, to
          award a lump sum in satisfaction of all claims and
          damages.
      (b) a single sum paid once in satisfaction of a claim, as
          contrasted with the alternate choice of several
          payments over a period of time; -- sometimes allowed,
          e.g., as an alternative to periodical pension payments
          for a lifetime.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lump \Lump\, v. i. [imp. & p. p. Lumped; p. pr. & vb. n.
   Lumping.]
   1. To throw into a mass; to unite in a body or sum without
      distinction of particulars.
      [1913 Webster]

            The expenses ought to be lumped together. --Ayliffe.
      [1913 Webster]

   2. To take in the gross; to speak of collectively.
      [1913 Webster]

            Not forgetting all others, . . . whom for brevity,
            but out of no resentment to you, I lump all
            together.                             --Sterne.
      [1913 Webster]

   3. To get along with as one can, although displeased; as, if
      he doesn't like it, he can lump it. [Low]
      [1913 Webster]

WordNet (r) 3.0 (2006):

lump
    n 1: a compact mass; "a ball of mud caught him on the shoulder"
         [syn: ball, clod, glob, lump, clump, chunk]
    2: an abnormal protuberance or localized enlargement [syn:
       swelling, puffiness, lump]
    3: an awkward stupid person [syn: lout, clod, stumblebum,
       goon, oaf, lubber, lummox, lump, gawk]
    4: a large piece of something without definite shape; "a hunk of
       bread"; "a lump of coal" [syn: hunk, lump]
    v 1: put together indiscriminately; "lump together all the
         applicants" [syn: lump, chunk]
    2: group or chunk together in a certain order or place side by
       side [syn: collocate, lump, chunk]

Moby Thesaurus II by Grady Ward, 1.0:

314 Moby Thesaurus words for "lump":
   abide, abide with, accumulation, acervation, agglomerate,
   agglomeration, aggregate, aggregation, allow, amassment, barrel,
   batch, bear, bear with, beard, bide, bilge, bit, blain, bleb,
   blend, blimp, blister, blob, block, body, boil, boss, bow, brave,
   brook, bubble, bulb, bulge, bulk, bulla, bump, bunch, bunion, burl,
   butt, butterfingers, button, cahot, cake, carbuncle, chine, chip,
   chunk, clabber, clip, clipping, clod, clot, clump, clumsy, cluster,
   coagulate, collect, collop, colophon, combine, comeuppance,
   concavity, concrete, concretion, condyle, congeal, congeries,
   conglobation, conglomerate, conglomeration, consolidate, convex,
   convexity, corn, crumb, cube, cumulation, curd, curdle, cut,
   cutting, cyst, dactylogram, dactylograph, dent, deserts, deserving,
   digest, dilatation, dilation, dint, distension, dollop, dowel, dub,
   due, duffer, ear, edema, embossment, end, endure, excrescence,
   fatty, fingerprint, flange, flap, footmark, footprint, footstep,
   foozler, fossil footprint, foul-up, fragment, fumble-fist,
   furuncle, gall, gathering, gawk, gel, gelatinate, gelatinize,
   glomeration, gnarl, gob, gobbet, goof, goofball, goofer, group,
   growth, handle, hang in, hang in there, hang tough, heap, heavy,
   heavyweight, hick, hill, hippo, hump, hunch, hunk, ichnite,
   ichnolite, impress, impression, imprint, incrassate, indent,
   indentation, indention, inspissate, intumescence, jell, jellify,
   jelly, jog, joggle, join, klutz, knob, knot, knur, knurl, lip,
   loaf, lobster, looby, loop, lopper, lot, lout, lubber, lummox,
   lump it, lump together, mass, merit, mix, modicum, moiety, mole,
   morsel, mountain, much, muff, muffer, nevus, node, nodule, nub,
   nubbin, nubble, nugget, oaf, pad, palooka, papilloma, paring,
   particle, pat, paw print, pawmark, peck, peg, persevere, piece,
   pile, pimple, pock, portion, potbelly, power, print, prominence,
   protrusion, protuberance, pug, pugmark, pustule, put together,
   put up with, quantity, rasher, rib, ridge, rights, ring, rising,
   roly-poly, rube, scoop, scrap, seal, sebaceous cyst, set, shard,
   shaving, shiver, shoulder, shred, sight, sigil, signet, slice,
   sliver, slob, smithereen, snack, snatch, snip, snippet, snowball,
   solid, solid body, spine, splinter, stamp, stand, stand for, step,
   stick, stitch, stockpile, stomach, stud, stumblebum, stumblebunny,
   stump, style, suffer, support, sustain, swagbelly, swallow, swell,
   swelling, swollenness, tab, take, take up with, tatter, thick,
   thicken, throw together, thumbmark, thumbprint, tolerate, tub,
   tub of lard, tubercle, tubercule, tumefaction, tumescence,
   tumidity, tumor, tun, turgescence, turgescency, turgidity, unite,
   verruca, vesicle, vestige, wad, wale, wart, wedge, welt, wen