Of all eight parts of speech that Mr Nurhadi taught me back at highschool (verb, noun, pronoun, adjective, adverb, preposition, conjunction, and interjection), I’ve always hated adjectives. The reason behind such animosity is mostly the fact that the mere function they offer is to compare.
You’re only beautiful since there are ugly people at other parts of the city. You’re perceived fat because there are skinny people around. The word tall would never even emerge if there aren’t height differences between people.
“Not tall enough, architects. Build some more!”
No matter what adjective you put in a sentence, add ‘not’ and voila! There, you got the exact adverse word. Even the word neutral distinguish you from the not neutral (either rightist or leftist) people. Shall you find any adjective that doesn’t go with its opposite, I might finally die in peace.
The lesson learned tonight is, whatever label people put on your head, fashion, or friendship, you should not waste your precious time on minding about it. They might use any adjectives to either compliment or bring you down, yet you know exactly that you’re the only person who knows what you’re worth.
The Conundrum Journal 
Actually adding the ‘not’ in seeking for the opposite of an adjective is linguistically ‘cheating’. ;)But, well, we have adjectified-derivatives (excuse my language) that don’t necessarily come with their antagonistic counterparts.Take the word HORARY, for instance. Well, what is the opposite of ‘pertaining to an hour’? MINUTELY or SECONDLY or DAILY or WEEKLY? Not exactly opposites, I believe.Even if we put it NOT HORARY, I still think it is not justified to say that NOT HORARY is definitely the opposite of HORARY. NOT HORARY is just not horary. And it can be anything but the adverse word for HORARY.Love your rhetoric, by the way. :)