1.  ingredient(n = noun.artifact) - a component of a mixture or compound;

2.  ingredient(n = noun.cognition) component, constituent, element, factor - an abstract part of something; "a key factor in her success"; "humor: an effective ingredient of a speech"; "jealousy was a component of his character"; "the grammatical elements of a sentence"; "two constituents of a musical composition are melody and harmony"

3.  ingredient(n = noun.food) fixings - food that is a component of a mixture in cooking; "the recipe lists all the fixings for a salad"

   That which enters into a compound, or is a component part of any combination, recipe, or mixture; an element; a constituent. [1913 Webster]

   Entering as, or forming, an ingredient or component part. [1913 Webster]

ingredient, n. a component part or element in a recipe, mixture, or combination.

Etymology:
ME f. L ingredi ingress- enter (as IN-(2), gradi step)

N  component, component part, integral part, integrant part, element, constituent, ingredient, leaven, part and parcel, contents, appurtenance, feature, member, personnel, forming, inclusive.