knocker

noun
1
a metal object attached to the outside of the door of a house, etc. that you hit against the door to attract attention
کوبه در, کوبه, کوبه درب
2
a person who is always criticizing somebody/something
منتقد, ایرادگیر, عیب‌جو, منتقد دائمی, نق‌زن, مدام ایرادگیر
3
a woman’s breasts
پستان, سینه