The Collaborative International Dictionary of English v.0.48:

Ingredient \In*gre"di*ent\, n. [F. ingr['e]dient, L. ingrediens,
   -entis, entering into, p. pr. of ingredi, p. p. ingressus, to
   go into, to enter; pref. in- in + gradi to walk, go. See
   Grade.]
   That which enters into a compound, or is a component part of
   any combination, recipe, or mixture; an element; a
   constituent.
   [1913 Webster]

         By way of analysis we may proceed from compounds to
         ingredients.                             --Sir I.
                                                  Newton.
   [1913 Webster]

         Water is the chief ingredient in all the animal fluids
         and solids.                              --Arbuthnot.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ingredient \In*gre"di*ent\, a.
   Entering as, or forming, an ingredient or component part.
   [1913 Webster]

         Acts where no sin is ingredient.         --Jer. Taylor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ingredient
    n 1: a component of a mixture or compound
    2: an abstract part of something; "jealousy was a component of
       his character"; "two constituents of a musical composition
       are melody and harmony"; "the grammatical elements of a
       sentence"; "a key factor in her success"; "humor: an
       effective ingredient of a speech" [syn: component,
       constituent, element, factor, ingredient]
    3: food that is a component of a mixture in cooking; "the recipe
       lists all the fixings for a salad" [syn: ingredient,
       fixings]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "ingredient":
   adjunct, appurtenance, aspect, census, circumstance, component,
   composition, constituent, constituents, content, contents, detail,
   divisions, element, elements, factor, feature, fixings, guts,
   index, ingredients, innards, insides, integrant, inventory, item,
   items, list, makings, part, part and parcel, parts, specialty,
   whole