foundation, grounding -- (education or instruction in the fundamentals of a field of knowledge; "he lacks the foundation necessary for advanced study"; "a good grounding in mathematics")
basis, base, foundation, fundament, groundwork, cornerstone -- (the fundamental assumptions from which something is begun or developed or calculated or explained; "the whole argument rested on a basis of conjecture")
foundation garment, foundation -- (a woman's undergarment worn to give shape to the contours of the body)