duller Synonyms

more vapid thudding Rainier drearier dimmer empty-headed uninteresting witless wearisome tedious stupid softened muted fainter more lifeless more lacklustre more lackluster foolisher less prudent ignoranter unrelieved unvaried slower unintelligent sluggish slow simpler edgeless dumb dreary drabber drab dismal dark colorless cloudy characterless boring enervated faint overcast muffled monotonous listless lethargic leaden languid irksome gloomy flatter