Meaning of a fortiori*

a for•ti•o•ri

Pronunciation: (ä fōr"ti-ō'rē Eng. ā fôr"shē-ôr'ī, ā fōr"shē-ōr'ī), [key]
— Latin. Latin.
  1. for a still stronger reason; even more certain; all the more.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.