irregardless

My superior intuition about the prefix in irregardless is that it is the same intensifier as the in- in inflammable. The prefix in- (also il-, im-, or ir-) in Latin was not only used for negation, it was an intensifier, also. There was also another, third, meaning of 'in, into, on' as in invade or invent (literally 'come upon', 'find', etc.

Ceci n'est pas un seing.