IPA: /ɪˈnɜːrbeɪn/
KK: /ɪnˈɜrbeɪn/
Not polite or refined; lacking sophistication or good manners.
His inurbane behavior at the dinner party surprised everyone.
Comparative: more inurbane
Superlative: most inurbane
Inurbane is formed from "in-" (meaning not) and "urbane" (from Latin "urbanus", meaning of the city or cultured). The word describes someone who is not cultured or refined, lacking the sophistication associated with urban life.
Think of 'not' ('in-') being combined with 'cultured' ('urbane') to remember that inurbane means lacking refinement or sophistication.