As a language it is easy, and anyone can see
To reverse the meaning of a word is elementary
To say ‘not well’ is 2 words. Why not pare it down to one?
Just take a word and prefix it. To reverse it just add ‘Un’

‘Un’well is also poorly, which is never any fun
The opposite of doing it, is leaving it ‘Un’done
If it ain’t fair it’s ‘Un’fair. If not kind then it’s ‘Un’kind
A contract with no autograph is a paper that’s ‘Un’signed

So like I said it’s unhard to make a word reverse
Simply add an ‘Un’ to it and it becomes its own inunverse
But so often with the language a rule can be misunleading
And there are other prefixes. To learn them keep on reading

It’s ‘A’ if it’s not typical, which might sound rather bland
But a ‘Mis’ if you can’t fire or you didn’t understand
It’s an ‘Il’ if its not legal, but an ‘In’ if unsecure
An ‘Ir’ makes it not regular and an ‘Im’ says it’s unpure

It’s a ‘Dis’ to uncontinue, it’s a ‘Post’ if it’s not ‘Pre’
It’s not ‘Un’ but prefix ‘Counter’ if you fight insurgency  
A friend nor longer friendly is not an ‘Un’friend but an ‘Ex’
But yes, it is the prefix ‘Un’ if it’s not what you expect

I will ‘An’ to your aerobic I will ‘Anti’ to your freeze
I will ‘Non’ if it is undescript just to put you at your ease
This might seem overwhelming but before I simplify
Please note if things are humid you should ‘De’humidify

So check if it’s an ‘Il’ an ‘In’ an ‘Ir’ an ‘Im’ or ‘dis’
A ‘Counter’, ‘Anti’, ‘Post’ or ‘De’ an ‘A,’ ‘An’ ‘Ex or ‘Mis’
If these are unappropriate when all is said and done
Yes, there is a modest chance the prefix might be ‘Un’

But in case you think you’ve got it; you’ve still got much to learn
Both flammable and ‘In’flammable mean the thing can burn