Meaning of leading coefficient

lead'ing coeffi'cient

Pronunciation: (lē'ding), [key]
— Math. Math.
  1. the coefficient of the term of highest degree in a given polynomial. 5 is the leading coefficient in 5x + 3x − 2x + 1.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.