DURO (Portuguese) adjective. 1 Boner 2. Hard-on 3 Rocklike 4. Firm Marcelo Mastro is a force to be reckoned with hard abs, hard dick, and three extra hard dildos. When Marcelo wants to fuck, no ass is safe. In this romp through the Brazilian countryside, watch as Marcelo and 8 other Brazilian natives explore the harder side of life. DURO is HARDCORE.