The Collaborative International Dictionary of English v.0.48:

Irradiate \Ir*ra"di*ate\ ([i^]r*r[=a]"d[i^]*[=a]t), v. t. [imp.
   & p. p. Irradiated ([i^]r*r[=a]"d[i^]*[=a]`t[e^]d); p. pr.
   & vb. n. Irradiating ([i^]r*r[=a]"d[i^]*[=a]`t[i^]ng).] [L.
   irradiatus, p. p. of irradiate. See In- in, and Radiate.]
   [1913 Webster]
   1. To throw rays of light upon; to illuminate; to brighten;
      to adorn with luster.
      [1913 Webster]

            Thy smile irradiates yon blue fields. --Sir W.
                                                  Jones.
      [1913 Webster]

   2. To enlighten intellectually; to illuminate; as, to
      irradiate the mind. --Bp. Bull.
      [1913 Webster]

   3. To animate by heat or light. --Sir M. Hale.
      [1913 Webster]

   4. To radiate, shed, or diffuse.
      [1913 Webster]

            A splendid fa[,c]ade, . . . irradiating hospitality.
                                                  --H. James.
      [1913 Webster]

   5. To expose to radiation of any kind, especially ionizing
      radiation; as, to sterilize food by irradiating it with
      gamma rays; one can cause mutations in bacteria by
      irradiating them with ultraviolet light.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

irradiate \ir*ra"di*ate\, v. i.
   To emit rays; to shine.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

irradiate \ir*ra"di*ate\ ([i^]r*r[=a]"d[i^]*[asl]t), a. [L.
   irradiatus, p. p.]
   Illuminated; irradiated. --Mason.
   [1913 Webster]

WordNet (r) 3.0 (2006):

irradiate
    v 1: give spiritual insight to; in religion [syn: enlighten,
         irradiate]
    2: cast rays of light upon
    3: expose to radiation; "irradiate food" [syn: irradiate,
       ray]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "irradiate":
   X-ray, activate, anhydrate, beacon, blast-freeze, brighten,
   brighten up, brine, charge, contaminate, corn, cure, dehydrate,
   desiccate, dry, dry-cure, dry-salt, edify, embalm, enlighten,
   evaporate, flood with light, floodlight, freeze, freeze-dry, fume,
   highlight, illume, illuminate, illumine, improve, infect, jerk,
   kipper, light, light up, lighten, luminate, marinade, marinate,
   mummify, overshine, pickle, poison, preservatize, quick-freeze,
   radiumize, refrigerate, relume, relumine, roentgenize, salt,
   season, shed light upon, shine upon, smoke, smoke-cure, spotlight,
   stuff, throw light upon, uplift