Uncommon is the closest, but here are some others: abnormal, extraordinary, infrequent, noteworthy, rare, scarce, uncommon, unusual, valuable, cultured, excellent, high, noble, refined, sophisticated, superior.
Distance or remoteness
Rare means uncommon, or unusual. So an obvious antonym ( opposite ) would be common. Other opposites are frequent, occuring , etc.. practically any word that shows multiples.
an antonym is a word opposite in meaning.
Hard, loud, rough.
Not flexible or having no flexibility
The word is Cowardice.
Leniency
A synonym of course. An antonym for a word that is defined for hvaing the opposite or nearly the opposite meaning.
Servant
unethical.
immoral, unethical
savant.
Smooth
Defeated
dawdle
ordinary, common
The opposite of unusual is common.