This depends on which definitions you work with. If you consider polynomials "any expression of \sum^n_{i=0}(c_i x^i) then sure, setting n=0 gets you "a polynom

This depends on which definitions you work with. If you consider polynomials "any expression of \sum^n_{i=0}(c_i x^i) then sure, setting n=0 gets you "a polynomial that is a constant function". If you take polynomials to be "functions that are expressions of weighted terms" then constant functions are out, and the set of functions described by the previous summation contains, but is itself larger than, the set of possible polynomials.