Possibly a double entendre. A neologism that could describe something as similar to Voltaire's antihero Candide; or, possibly, describing an object as similar to the yeast Candida albicans. Both seem to be applicable to the Infinite Jest character (Prince Q―) described by this word.
Indeed, given the discussion later in the book of various molds and even molds that grow only on other molds, it would appear that the second definition previously offered would be the more correct one. However, I still assert that Prince Q— could be likened to Candide and thus candidiatic is in fact a double entendre.