The Rice University Neologisms Database

Someone with an uncountably large (infinite) amount of money. A billion is a huge number, but to a mathematician trying to contrast very large finite numbers with truly infinite numbers, a billion was not enough. Professor Berend used money instead of numbers to illustrate this difference, and in the process, coined infinitionaire. Analogous to millionaire, and produced by blending, infinitionaire carries connotations of truly uncountable sums of money. The neologism probably was never needed in real life; a billionaire has, for all practical purposes, infinite wealth. But, in mathematics, finite and infinite numbers have drastically different mathematical properties and implications. By coining this neologism to explain series convergence (to a finite number) / divergence (to infinity), such a distinction was successfully made. Interestingly, milli originally meant ‘thousand’ – but the meaning somehow shifted to a ‘thousand thousand.’ The word is difficult and awkward to pronounce, probably since both blended components are borrowed (foreign) multimorphemic words – already a mouthful alone.