knob 
/ˈnɑ:b/ noun
plural knobs /ˈnɑ:b/ noun [count] 1 : a round switch on a television, radio, etc.
▪ The left knob [=dial] controls the volume. 2 : a round handle on a door, drawer, etc.
▪ The knob [=doorknob] is stuck and I can't open the door! ▪ a carved walking stick with a silver knob 3 chiefly Brit : a small lump or piece of something
▪ a knob of butter/coal 4 Brit, informal + impolite : penis
▪ The left knob [=dial] controls the volume.
▪ The knob [=doorknob] is stuck and I can't open the door! ▪ a carved walking stick with a silver knob
▪ a knob of butter/coal
with knobs on
Brit, informal : with extra things added
▪ The movie is just an ordinary thriller with knobs on.
▪ The movie is just an ordinary thriller with knobs on.
