<P> Illegitimi non carborundum is a mock - Latin aphorism meaning "Don't let the bastards grind you down". </P> <P> The word illegitimi (i.e., the plural of illegitimus, actually translates to "unlawful" or "outlaw" but resembles the English "illegitimate") is sometimes given in the plural dative case (that is, illegitimīs), a case that follows the Latin gerundive and denotes agency . Non negates activity . Carborundum is an industrial abrasive material also known as silicon carbide, but its name resembles a Latin gerundive, a grammatical construct that expresses desirability of whatever the verb denotes . So carborundum can be mock - translated to mean "fit to be ground". Thus "illegitimi (s) non carborundum" would mean "not fit to be ground by the illegitimate", or "Don't let the bastards grind you down". </P>

Latin motto don let the bastards get you down