knob /nɒb $ nɑːb/ BrE AmE noun [countable]
[ Date: 1300-1400 ; Language: Middle Low German ; Origin: knobbe ]
1 . a round handle or thing that you turn to open a door, turn on a television etc:
He thought the door was locked, but he turned the knob and the door opened.
a brass door knob
I adjusted the volume knob and sat down.
2 . a knob of something a small piece of something SYN lump :
Melt a knob of butter in the pan.
3 . British English spoken not polite a ↑ penis
4 . with (brass) knobs on British English spoken old-fashioned used especially by children to reply to an insult:
‘You’re fat and lazy.’ ‘Fat and lazy to you with brass knobs on!’