The Collaborative International Dictionary of English v.0.48:

Grease \Grease\ (gr[=e]z or gr[=e]s; 277), v. t. [imp. & p. p.
   Greased (gr[=e]zd or gr[=e]sd); p. pr. & vb. n.
   Greasing.]
   [1913 Webster]
   1. To smear, anoint, or daub, with grease or fat; to
      lubricate; as, to grease the wheels of a wagon.
      [1913 Webster]

   2. To bribe; to corrupt with presents.
      [1913 Webster]

            The greased advocate that grinds the poor. --Dryden.
      [1913 Webster]

   3. To cheat or cozen; to overreach. [Obs.] --Beau. & Fl.
      [1913 Webster]

   4. (Far.) To affect (a horse) with grease, the disease.
      [1913 Webster]

   To grease in the hand, To grease the hand, to corrupt by
      bribes. --Usher.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grease \Grease\ (gr[=e]s), n. [OE. grese, grece, F. graisse;
   akin to gras fat, greasy, fr. LL. grassus thick, fat, gross,
   L. crassus. Cf. Crass.]
   1. Animal fat, as tallow or lard, especially when in a soft
      state; oily or unctuous matter of any kind.
      [1913 Webster]

   2. (Far.) An inflammation of a horse's heels, suspending the
      ordinary greasy secretion of the part, and producing
      dryness and scurfiness, followed by cracks, ulceration,
      and fungous excrescences.
      [1913 Webster]

   Grease bush. (Bot.) Same as Grease wood (below).

   Grease moth (Zool.), a pyralid moth (Aglossa pinguinalis)
      whose larva eats greasy cloth, etc.

   Grease wood (Bot.), a scraggy, stunted, and somewhat
      prickly shrub (Sarcobatus vermiculatus) of the Spinach
      family, very abundant in alkaline valleys from the upper
      Missouri to California. The name is also applied to other
      plants of the same family, as several species of
      Atriplex and Obione.
      [1913 Webster]

WordNet (r) 3.0 (2006):

grease
    n 1: a thick fatty oil (especially one used to lubricate
         machinery) [syn: grease, lubricating oil]
    2: the state of being covered with unclean things [syn: dirt,
       filth, grime, soil, stain, grease, grunge]
    v 1: lubricate with grease; "grease the wheels"

Moby Thesaurus II by Grady Ward, 1.0:

175 Moby Thesaurus words for "grease":
   Trinkgeld, adulation, aid, animal oil, anoint, approach, beeswax,
   blandishment, blarney, blunt, bonus, boodle, bounty, brass, bread,
   bribe, bucks, bunkum, buy, buy off, cabbage, cajolement, cajolery,
   cerate, chips, clear the way, compliment, consideration, corrupt,
   dab, daub, dinero, donative, double time, dough, drag, dress,
   drying oil, dub, ease, embrocate, equalize, essential oil, ester,
   even, expedite, explain, eyewash, facilitate, fair words, fat,
   fatty oil, fawning, fee, fix, fixed oil, flatten, flattery, gelt,
   get at, get to, gilt, glycerolate, grade, gratuity, gravy,
   grease the palm, grease the ways, grease the wheels, green,
   green stuff, harrow, hasten, help along, honeyed phrases,
   honeyed words, honorarium, hydrogenated fat, incense,
   incentive pay, inducement, jack, kale, lagniappe, lard, largess,
   lay, level, liberality, lipid, loose, lubricate, make clear,
   make way for, mazuma, mineral oil, moolah, mopus, mow, oil,
   oil of palms, ointment, oleum, oof, ooftish, open the way, open up,
   palaver, palm oil, pave the way, pay off, perks, perquisite, plane,
   planish, plaster, polyunsaturated fat, pomade, pourboire, praise,
   premium, prepare the way, pretty lies, purchase, quicken, reach,
   remove friction, rhino, rocks, run interference for, salve, sebum,
   shave, shekels, simoleons, simplify, slick, slick on, smear,
   smooth, smooth down, smooth out, smooth the way, soap,
   soap the ways, soft soap, something extra, speed, spondulics,
   sportula, suborn, sugar, sweet nothings, sweet talk, sweet words,
   sweetener, sycophancy, take care of, tallow, tamper with,
   the needful, tickle the palm, tin, tip, unbar, unblock, unclog,
   unguent, unjam, unsaturated fat, vegetable oil, volatile oil,
   wampum, wax, wheedling