Oxford Advanced American Dictionary

Definition of better adjective from the Oxford Advanced Learner's Dictionary

Oxford3000

better

adjective
better pronunciation English ˈbetə(r) better pronunciation American ˈbetər
 
(comparative of good)1 of a higher standard or less poor quality; not as bad as something elseWe're hoping for better weather tomorrow.Her work is getting better and better.He is in a much better mood than usual.The meal couldn't have been better.There's nothing better than a long soak in a hot bath.If you can only exercise once a week, that's better than nothing (= better than taking no exercise at all).2 more able or skilledShe's far better at science than her brother.3 more suitable or appropriateCan you think of a better word than ‘nice’?It would be better for him to talk to his parents about his problems.You'd be better going by bus.4 less ill/sick or unhappyShe's a lot better today.His leg was getting better.You'll feel all the better for a good night's sleep.5 fully recovered after an illness; in good health againDon't go back to work until you are better. see also well adjective
Idioms
Most idioms containing better are at the entries for the nouns and verbs in the idioms, for example better luck next time is at luck. 

little/no better than

almost or just the same as; almost or just as bad as
The path was no better than a sheep track.

that's (much) better

1 used to give support to somebody who has been upset and is trying to become calmerDry your eyes now. That's better.2 used to praise somebody who has made an effort to improveThat's much better—you played the right notes this time.

the bigger, smaller, faster, slower, etc. the better

used to say that something should be as big, small, etc. as possible
As far as the hard disk is concerned, the bigger the better.
more at discretion is the better part of valour at discretion, two heads are better than one at head noun, the best/better part of something at part noun, prevention is better than cure at prevention