generous - mean, stingy
yes
Greedy,Selfish,Self-centered,Ungiving.
They are antonyms of one another.
The opposite (antonym) of antonym is synonym. An antonym is a word that means the opposite. A synonym is a word that means the same thing, or nearly the same thing, for a given context.
Give things to the poor. All you have to do is be kind. Giving things, like your help, is generous.