duller Synonyms

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