The Collaborative International Dictionary of English v.0.48:

Polynomial \Pol`y*no"mi*al\, n. [Poly- + -nomial, as in
   monomial, binomial: cf. F. polyn[^o]me.] (Alg.)
   An expression composed of two or more terms, connected by the
   signs plus or minus; as, a^2 - 2ab + b^2.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Polynomial \Pol`y*no"mi*al\, a.
   1. Containing many names or terms; multinominal; as, the
      polynomial theorem.
      [1913 Webster]

   2. Consisting of two or more words; having names consisting
      of two or more words; as, a polynomial name; polynomial
      nomenclature.
      [1913 Webster]

WordNet (r) 3.0 (2006):

polynomial
    adj 1: having the character of a polynomial; "a polynomial
           expression" [syn: polynomial, multinomial]
    n 1: a mathematical function that is the sum of a number of
         terms [syn: polynomial, multinomial]

The Free On-line Dictionary of Computing (30 December 2018):

polynomial

   1.  An arithmetic expression composed by summing
   multiples of powers of some variable.

   	P(x) = sum a_i x^i for i = 0 .. N

   The multipliers, a_i, are known as "coefficients" and N, the
   highest power of x with a non-zero coefficient, is known as
   the "degree" of the polynomial.  If N=0 then P(x) is constant,
   if N=1, P(x) is linear in x.  N=2 gives a "quadratic" and
   N=3, a "cubic".

   2.  polynomial-time.