Meaning of preprocessor

pre•proc•es•sor

Pronunciation: (prē'pros"es-ur, -u-sur or, esp. Brit., -prō"ses-ur, -su-sur), [key]
— n. Computers.
  1. a program that performs some type of processing, as organization of data or preliminary computation, in advance of another program that will perform most of the processing.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.