It is common in legal writing to aver, meaning to allege, assert, or affirm a fact. (Latin root is adver.)
But I can't find any evidence that the obvious noun form of the word, aversion, has ever been used as such. Instead, aversion has always and only been the noun form of avert, derivative of the Latin root avers (meaning something like to turn away).
I.e., it seems like the avert verb root blocked the noun form aversion from being used with the aver verb. Is this correct? If so, is there a term for this sort of conflict and deconfliction in English (or in linguistics more generally)?