the bottom or base of anything; the part on which something stands or rests.
anything upon which something is based; fundamental principle; groundwork.
the principal constituent; fundamental ingredient.
a basic fact, amount, standard, etc., used in making computations, reaching conclusions, or the like: The nurse is paid on an hourly basis. He was chosen on the basis of his college grades.
a set of linearly independent elements of a given vector space having the property that every element of the space can be written as a linear combination of the elements of the set.