1.noun(strict sense) An expression consisting of a sum of a finite number of terms, each term being the product of a constant coefficient and one or more variables raised to a non-negative integer power, such as a_n x^n + a_{n-1}x^{n-1} + ... + a_0 x^0.
2.nounA taxonomic designation (such as of a subspecies) consisting of more than two terms.