0 a round handle, or a small, round device for controlling a machine or electrical equipment -- 球形把手;(機器等的)旋鈕
1 a small amount of something solid, especially butter -- (尤指奶油)小塊
2 a penis -- 陰莖
Twiddle a knob on a radio in Britain and you may hear more voices speaking crackly French or German than English.
At the twiddle of a knob the operators can focus on a tiny amount of airspace or scan the whole area.