The Collaborative International Dictionary of English v.0.48:

Season \Sea"son\, v. t. [imp. & p. p. Seasoned; p. pr. & vb.
   n. Seasoning.]
   1. To render suitable or appropriate; to prepare; to fit.
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            He is fit and seasoned for his passage. --Shak.
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   2. To fit for any use by time or habit; to habituate; to
      accustom; to inure; to ripen; to mature; as, to season one
      to a climate.
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   3. Hence, to prepare by drying or hardening, or removal of
      natural juices; as, to season timber.
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   4. To fit for taste; to render palatable; to give zest or
      relish to; to spice; as, to season food.
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   5. Hence, to fit for enjoyment; to render agreeable.
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            You season still with sports your serious hours.
                                                  --Dryden.
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            The proper use of wit is to season conversation.
                                                  --Tillotson.
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   6. To qualify by admixture; to moderate; to temper. "When
      mercy seasons justice." --Shak.
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   7. To imbue; to tinge or taint. "Who by his tutor being
      seasoned with the love of the truth." --Fuller.
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            Season their younger years with prudent and pious
            principles.                           --Jer. Taylor.
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   8. To copulate with; to impregnate. [R.] --Holland.
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The Collaborative International Dictionary of English v.0.48:

Seasoning \Sea"son*ing\, n.
   1. The act or process by which anything is seasoned.
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   2. That which is added to any species of food, to give it a
      higher relish, as salt, spices, etc.; a condiment.
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   3. Hence, something added to enhance enjoyment or relieve
      dullness; as, wit is the seasoning of conversation.
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            Political speculations are of so dry and austere a
            nature, that they will not go down with the public
            without frequent seasonings.          --Addison.
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   Seasoning tub (Bakery), a trough in which dough is set to
      rise. --Knight.
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WordNet (r) 3.0 (2006):

seasoning
    n 1: something added to food primarily for the savor it imparts
         [syn: flavorer, flavourer, flavoring, flavouring,
         seasoner, seasoning]
    2: the act of adding a seasoning to food

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "seasoning":
   ability, acclimation, acclimatization, accommodation, accustoming,
   adaption, adjustment, aging, anhydration, background,
   beautification, blaseness, blast-freezing, bottling, breaking,
   breaking-in, brining, canning, capability, case hardening,
   competence, competency, condiment, condiments, condition,
   conditioning, corning, curing, dash, dehydration, desiccation,
   development, domestication, dry-curing, drying, elaboration,
   embalming, embellishment, evaporation, evolution, experience,
   familiarization, fitness, fittedness, flavor, flavorer, flavoring,
   freeze-drying, freezing, fuming, habituation, hardening, hint,
   housebreaking, infusion, inkling, intimation, inurement,
   irradiation, jerking, marination, mastery, maturation,
   maturescence, maturity, mellowing, mummification, naturalization,
   orientation, past experience, perfection, pickling, potting,
   practical knowledge, practice, preparedness, proficiency,
   qualification, quick-freezing, readiness, refinement,
   refrigeration, relish, ripeness, ripening, sagacity, salting,
   sauce, seasoner, senescence, shade, smack, smoking, sophistication,
   soupcon, spice, sprinkling, stuffing, suggestion, suitability,
   suitableness, suitedness, suspicion, taint, taming, taxidermy,
   tempering, thought, tinct, tincture, tinge, tinning, tint, touch,
   trace, training, trim, vestige, worldly wisdom, zest