1. Dull, blunt refer to the edge or point of an instrument, tool, or the like. Dull implies a lack or a loss of keenness or sharpness: a dull razor or saw. Blunt may mean the same or may refer to an edge or point not intended to be keen or sharp: a blunt or stub pen; a blunt foil. 7. Dull, blunt, slow, stupid are applied to mental qualities. Dull implies obtuseness, lack of imagination: a dull child. Blunt implies loss of original keenness of intelligence through disease, sad experience, or the like: His critical faculties were blunt. Slow applies to a sluggish intellect: a slow mind. Stupid implies slowness of mental processes, but also lack of intelligence, wisdom, prudence, etc.: a stupid person.

Did you mean culling?