The Oxford Thesaurus An A-Z Dictionary of Synonyms - foundationn.

1) basis, base, substructure, understructure, underpinning, bottom, foot, basement, cellar: This foundation is of stone. 2) basis, base, fundamental, (underlying or fundamental) principle, grounds, groundwork, rationale, raison d'€tre, purpose: Their morality finds its foundations in Judaeo-Christian culture. 3) founding, establishment, instituting, institution, creation, origination, setting up, organizing, organization, inauguration, endowment: We voted for the foundation of an institute to study the English language.