megalonisus: this is a greco-latin compound word, probably of recent date: megalos (greek, well known) = big, and nisus, less well known, latin, striving, see
http:// www.perseus.tufts.edu/cgi-bin/lexindex?lookup=nisus&type=begin&options=Sort+Results+Alphabetically&lang=la#nisus#1 . "Nikhedonia" appears to me an even more blatantly modern construct from nikao (greek, I win) and hedonia (greek, pleasure). I should not be surprised if it turned out to be created by a German (given the order of the component words)..