1) Today is fairly better. - Better is usually modified with an attribute of size or quantity, not quality. So you will say 'not much better, lots better, a little better etc. 2) His condition is rather worse. - In British English, this is acceptable but the phrasing is very specific to Britain. Again, like Better, you would use a quantity modifier. His condition is a little worse, much worse, a lot worse. 3) His opinion is much better - it's good, but 'better' modifies 'opinion'. if it's connected to the first two sentences, you might be looking for something like: 'in the doctors opinion, he is getting much better' or 'in my opinion, he is much better' Hope this helps!