Hi anchita!

if there is a named category for words that combine two word-elements with opposing meanings

But..but..but (scratching head e)isn't THAT what an oxymoron is!!!?? It appears you are referring to words that are not only oxymorons but are also derived from them? A sub-class, maybe?

hmmmm....I imagine oxymorons are mostly phrases concocted with INTENT, for effect; catch phrases designed to project contradiction. And funny though they sound, they ALWAYS mean something and manage to convey it effectively too.

What would be the purpose in creating a contradictory word that derives from similarly inconsistent roots? Take sophomore, for e.g., WHY was it constructed that way? For what purpose or to what end? Are we looking at these roots right, or are we seeing some dendritic mingling with other words over time?