n. Anything which takes the liberty to differ from other things of its class, such as an honest man or a truthful woman.
"The exception proves the rule" is an expression constantly upon the lips of the ignorant, who parrot it from one another with never a thought of its absurdity. In the Latin, "Exceptio probat regulam" means that the exception tests the rule, puts it to the proof, not confirm it. The malefactor who drew the meaning from this excellent dictum and substituted a contrary one of his own exerted an evil power which appears to be immortal.
— Ambrose Bierce