Source : Webster's Revised Unabridged Dictionary (1913)

Knobbing \Knob"bing\, n. (Stone Quarrying)
   Rough dressing by knocking off knobs or projections.

Source : WordNet®

knob
     n 1: a circular rounded projection or protuberance [syn: {boss}]
     2: a round handle
     3: any thickened enlargement [syn: {node}, {thickening}]
     4: an ornament in the shape of a ball on the hilt of a sword or
        dagger [syn: {pommel}]
     [also: {knobbing}, {knobbed}]

knobbing
     See {knob}