Sentence:  For this purpose, a <WSD>polynomial basis</WSD> is used here, which consists of all monomials in the scheduling signals up to a fixed total order. Such a <WSD>polynomial basis</WSD> can be interpreted as the polynomial terms, which would appear in a multivariate Taylor approximation of the unknown scheduling function. 
Meaning of the word marked with <WSD> tags:  A basis of a polynomial ring (said ring being viewed either as a vector space over the field of coefficients or as a free module over the ring of coefficients).