The opposite of master is servant or apprentice.
opposite
The opposite of think would usually be act.The opposite of think (believe) could be doubt.The opposite motivation from think (use intellect) would be to feel (use emotion).
The opposite of refute is to prove correct.
The opposite of duty is freedom or choice.
The opposite of shouldn't (should not) is should.
To purchase means to buy. Therefore the opposite should be: to sell
The wing of the chicken allows flight therefore the opposite should be the feet.
It should be a basin in my opinion.
If you have to be opposite on opposite day, that makes it a day, and then there was no opposite day. But that can't be true since you HAVE to be opposite, which means that you have to be normal even though there is an opposite day because you are supposed to be opposite on opposite day, which means that you act normal as if it was a normal day, because that is the opposite of opposite day. (This is a classic "liar's paradox". Since there is already an opposite day, you should have a normal day because that is the opposite of an opposite day. But then it is not an opposite day.)
You should have your head opposite from his/hers
The opposite (evil vs. good) would be villain. Though villainess should be the feminine, there is no such word in the English language.The opposite gender is hero.
We should really call it a camera obscura - literally a dark room - so I suppose the opposite should be a light room. Conservatory or sun lounge perhaps?
With proper respect
non- as in nonessential.
Bald, or 'clean-shaven' should do.
It should on the opposite side it got hit on