Isn't it possible that some or even all of these words used to be formed as augmentatives and just lost the connection to the basic word? The funny thing about Чудовище is that it's German counterpart "Ungeheuer" uses an augmentative prefix un-, but there is no "Geheuer" anymore either, outside of a single fixed phrase where it is an adjective meaning "understandable".
And does the former translate to "very smart large cat"? The second I don't get at all...Another interesting suffix is -ющ, used in adjectives:
Вдруг откуда-то хитрющий котище
И шипит он в длинющий усище.![]()