prettygoodword.livejournal.comparonym (PAR-uh-nim) - n., a word derived from the same root or stem as another word.
Or as most dictionaries tautologically define it, a paronymous word -- which they do because the adjective arrived in English two centuries before the noun (1650-ish versus 1846), even though in Greek the equivalent adjective is derived from the noun. This is not quite the same as a cognate, which is specifically paronyms in two different languages. Oh, as for that Greek root, parōnymon, from para-, derivative of + ónyma, name -- "from the same name".
Wise and wisdom are paronyms.
---L.