Real Dictionary

binomial theorem in American English
the general formula for the expansion of any binomial when raised to a power that is a positive whole number; the expansion of (a + b)n: discovered by Omar Khayyám and generalized by Sir Isaac Newton (Ex.: (a + b)2 = a2 + 2 ab + b2)
noun: the theorem giving the expansion of a binomial raised to any power

binomial theorem in British English
noun: a mathematical theorem that gives the expansion of any binomial raised to a positive integral power, n. It contains n + 1 terms: (x + a)n = xn + nxn–1a + [n(n–1)/2] xn–2a2 +…+ (nk) xn–kak + … + an, where (nk) = n!/(n– k)!k!, the number of combinations of