The Collaborative International Dictionary of English v.0.48:

Diffuse \Dif*fuse"\, v. t. [imp. & p. p. Diffused; p. pr. &
   vb. n. Diffusing.] [L. diffusus, p. p. of diffundere to
   pour out, to diffuse; dif- = dis- + fundere to pour. See
   Fuse to melt.]
   To pour out and cause to spread, as a fluid; to cause to flow
   on all sides; to send out, or extend, in all directions; to
   spread; to circulate; to disseminate; to scatter; as to
   diffuse information.
   [1913 Webster]

         Thence diffuse
         His good to worlds and ages infinite.    --Milton.
   [1913 Webster]

         We find this knowledge diffused among all civilized
         nations.                                 --Whewell.

   Syn: To expand; spread; circulate; extend; scatter; disperse;
        publish; proclaim.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Diffuse \Dif*fuse"\, v. i.
   To pass by spreading every way, to diffuse itself.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Diffuse \Dif*fuse"\, a. [L. diffusus, p. p.]
   Poured out; widely spread; not restrained; copious; full;
   esp., of style, opposed to concise or terse; verbose;
   prolix; as, a diffuse style; a diffuse writer.
   [1913 Webster]

         A diffuse and various knowledge of divine and human
         things.                                  --Milton.

   Syn: Prolix; verbose; wide; copious; full. See Prolix.
        [1913 Webster]

WordNet (r) 3.0 (2006):

diffuse
    adj 1: spread out; not concentrated in one place; "a large
           diffuse organization"
    2: (of light) transmitted from a broad light source or reflected
       [syn: soft, diffuse, diffused] [ant: concentrated,
       hard]
    3: lacking conciseness; "a diffuse historical novel"
    v 1: move outward; "The soldiers fanned out" [syn: diffuse,
         spread, spread out, fan out]
    2: spread or diffuse through; "An atmosphere of distrust has
       permeated this administration"; "music penetrated the entire
       building"; "His campaign was riddled with accusations and
       personal attacks" [syn: permeate, pervade, penetrate,
       interpenetrate, diffuse, imbue, riddle]
    3: cause to become widely known; "spread information";
       "circulate a rumor"; "broadcast the news" [syn: circulate,
       circularize, circularise, distribute, disseminate,
       propagate, broadcast, spread, diffuse, disperse,
       pass around]

Moby Thesaurus II by Grady Ward, 1.0:

289 Moby Thesaurus words for "diffuse":
   abounding, abundant, affluent, all-sufficing, ambagious, ample,
   aplenty, assign, atomize, bend, bespread, bestrew, bias,
   bottomless, bounteous, bountiful, break into pieces,
   break to pieces, break up, broad, broadcast, carry over, casual,
   circuitous, circulate, circumfuse, circumlocutory, communicate,
   consign, copious, crash, crawl with, creep with, crook, crunch,
   crush, curve, cut to pieces, deal out, deflect, deflected,
   deflective, deliver, demolish, deport, desultory, deviate,
   diffract, diffracted, diffractive, diffuse, diffused, diffusive,
   digressive, discrete, discursive, disjoin, dispel, dispense,
   disperse, dispersed, dispread, disrupt, disseminate, disseminated,
   dissipate, dissipated, distort, distorted, distribute, distributed,
   diverge, divert, dogleg, ease, ease off, effuse, effusive, emanate,
   epidemic, exhaustless, expand, expel, export, extend,
   extend throughout, extended, extensive, extradite, extravagant,
   exuberant, fan out, far-embracing, far-extending, far-flung,
   far-flying, far-going, far-ranging, far-reaching, fat, fecund,
   fertile, fill, fission, flectional, flexed, flush, formless,
   fragment, free, full, galore, generous, grind, gushing, gushy,
   hairpin, hand forward, hand on, hand over, honeycomb, imbue,
   impart, import, in plenty, in quantity, indiscriminate,
   inexhaustible, inflective, infuse, interlard, intersow,
   intersperse, intersprinkle, issue, large-scale, lasting, lavish,
   lax, leave no void, leaven, lengthy, let go, let up, liberal, long,
   long-drawn-out, long-winded, loose, loosen, loquacious, luxuriant,
   make mincemeat of, make over, many, maximal, meandering,
   metastasize, metathesize, mince, much, numerous, occupy, opulent,
   overflowing, overrun, overscatter, oversow, overspread, overswarm,
   pass, pass on, pass over, pass the buck, penetrate, perfuse,
   periphrastic, permeate, pervade, plenitudinous, plenteous,
   plentiful, plenty, pleonastic, prevailing, prevalent, prodigal,
   productive, profuse, profusive, prolific, prolix, prolonged,
   propagate, protracted, publish, pull, pulverize, radiate, rambling,
   rampant, random, ray, redundant, refract, refracted, refractile,
   refractive, refrangible, reiterative, relax, relay, repetitive,
   replete, retail, rich, rife, riotous, roundabout, run through,
   running over, scatter, scattered, shatter, shiver, skew, skewed,
   slack, slack off, slacken, smash, smash up, sow, sow broadcast,
   sparse, splay, splinter, sporadic, spread, spread out, squash,
   squish, straggling, straggly, strew, strewn, strown, suffuse,
   superabundant, swarm with, sweeping, switch, tautologous,
   teem with, teeming, transfer, transfer property, transfuse,
   translate, translocate, transmit, transplace, transplant,
   transpose, turn, turn over, twist, unglue, unleash, unstick, utter,
   verbose, warp, wealthy, well-found, well-furnished, well-provided,
   well-stocked, wholesale, wide, wide-extended, wide-extending,
   wide-ranging, wide-reaching, wide-stretching, widespread, windy,
   wordy, zigzag