[ fôr-mā′shē-ō ]
n. pl. for•ma•ti•o•nes (-mā′shē-ō′nēz)
A structure of definite shape or cellular arrangement; a formation.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for formatio
The formatio reticularis which is feebly developed in the cord becomes well developed in the medulla.