knoll(noun, verb) noun1. a small natural hillSimilar word(s): hammock, hillock, hummock, moundDefinition categories: object, hill verb1. To ring (a bell) mournfully; to knell.2. To sound, like a bell; to knell.- If ever been where bells have knoll´d to church.3. To arrange related objects in parallel or at 90 degree angles.