Ingredient, n.
Etymology: [F. ingrédient, 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 or mixture; an element; a constituent. By way of analysis we may proceed from compounds to ingredients. Sir I. Newton. Water is the chief ingredient in all the animal fluids and solids. Arbuthnot.
1 other Webster entry under this spelling
Ingredient, a.
Entering as, or forming, an ingredient or component part. Acts where no sin is ingredient. Jer. Taylor.
Shades of meaning
Fernald has no entry of its own for ingredient; he lists it under part.
Where he writes about it:
A component, constituent, ingredient, or element is a part of some compound or mixture; an element is necessary to the existence, as a component or constituent is necessary to the completeness of that which it helps to compose; an ingredient may be foreign or accidental. — from part