The Collaborative International Dictionary of English v.0.48:

Inspissate \In*spis"sate\, v. t. [imp. & p. p. Inspissated; p.
   pr. & vb. n. Inspissating.] [L. inspissatus, p. p. of
   inspissare to thicken; pref. in- + spissare to thicken, fr.
   spissus thick.]
   To thicken or bring to greater consistence, as fluids by
   evaporation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Inspissate \In*spis"sate\, a. [L. inspissatus, p. p.]
   Thick or thickened; inspissated. --Greenhill.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inspissate
    v 1: make viscous or dense; "thicken the sauce by adding flour"
         [syn: thicken, inspissate]
    2: make thick or thicker; "Thicken the sauce"; "inspissate the
       tar so that it becomes pitch" [syn: thicken, inspissate]
       [ant: thin]
    3: become thick or thicker; "The sauce thickened"; "The egg yolk
       will inspissate" [syn: thicken, inspissate] [ant: thin]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "inspissate":
   beat up, cake, caked, cakey, churn, clabber, clabbered, clot,
   clotted, clump, cluster, coagulate, coagulated, colloid,
   colloidize, concrete, congeal, congealed, cream, curd, curded,
   curdle, curdled, emulsify, emulsionize, fatten, gel, gelatinate,
   gelatinize, gelatinized, grow thick, grumous, incrassate,
   inspissated, jell, jelled, jellied, jellify, jelly, knot, lopper,
   lump, lumpish, lumpy, set, thick, thicken, thickened, whip