knob

柯林斯词典

1. N-COUNT A knob is a round handle on a door or drawer which you use in order to open or close it. 球形把手
He turned the knob and pushed against the door. 他转动门把手，推了那扇门。
2. N-COUNT A knob is a round switch on a piece of machinery or equipment. 旋钮
...the volume knob. …音量旋钮。

Turn the knob in a clockwise direction .
He pulled the knob and it just came off in his hand .
She turned the door knob and quietly opened the door .
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 .