The Collaborative International Dictionary of English v.0.48:

Subsidize \Sub"si*dize\, v. t. [imp. & p. p. Subsidized; p.
   pr. & vb. n. Subsidizing.] [From Subsidy.]
   To furnish with a subsidy; to purchase the assistance of by
   the payment of a subsidy; to aid or promote, as a private
   enterprise, with public money; as, to subsidize a steamship
   line.
   [1913 Webster]

         He employed the remittances from Spain to subsidize a
         large body of German mercenaries.        --Prescott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

subsidize
    v 1: support through subsidies; "The arts in Europe are heavily
         subsidized" [syn: subsidize, subsidise]
    2: secure the assistance of by granting a subsidy, as of nations
       or military forces [syn: subsidize, subsidise]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "subsidize":
   accommodate, afford, afford support, aid, angel, assist, back,
   back up, bankroll, bear, bear out, bear up, blow to, bolster,
   bolster up, brace, buoy up, buttress, capitalize, carry, clothe,
   contribute, cradle, crutch, cushion, donate, endow, fill, fill up,
   finance, find, fund, furnish, give, give support, go treat,
   grubstake, help, hold, hold up, invest, keep, keep afloat, keep up,
   lend support, mainstay, maintain, make available,
   make provision for, patronize, pay for, pay the bill,
   pay the bills, pension, pension off, pillow, prepare, present,
   promote, prop, prop up, provide, provide for, recruit, refinance,
   reinforce, replenish, set up, shore, shore up, shoulder, sponsor,
   stake, stand drinks, stand to, stand treat, stay, stock, store,
   subvene, subvention, subventionize, supply, support, sustain,
   treat, treat to, underbrace, undergird, underlie, underpin,
   underset, underwrite, upbear, uphold, upkeep, yield