bet·ter
[bet-er]

adjective, compar. of good with best as superl.
1. of superior quality or excellence: a better coat; a better speech.

2. morally superior; more virtuous: They are no better than thieves.

3. of superior suitability, advisability, desirability, acceptableness, etc.; preferable: a better time for action.

4. larger; greater: the better part of a lifetime.

5. improved in health; healthier than before.

6. completely recovered in health.

adverb, compar. of well with best as superl.
7. in a more appropriate or acceptable way or manner: to behave better.

8. to a greater degree; more completely or thoroughly: He knows the way better than we do. I probably know him better than anyone else.

9. more: I walked better than a mile to town.

verb (used with object)
10. to increase the good  qualities of; make better;  improve: to better the lot of the suburban commuter.

11. to improve upon; surpass; exceed: We have bettered last year’s production record.

12. Cards . to raise (a previous bid).

noun
13.that which has greater excellence or is preferable or wiser: the better of two choices.

14. Usually, betters. those superior to one in wisdom, wealth, etc.

Idioms
15. better off,
     a. in better circumstances.
     b. more fortunate; happier: Because of his asthma, he would be better off in a different climate.

16. better oneself, to improve one’s social standing, financial position, or education: He is going to night school because he wants to better himself.

17. for the better, in a way that is an improvement: His health changed for the better.

18. get / have the better of,
     a. to get an advantage over.
     b. to prevail against.

19. go (someone) one better, to exceed the effort of; be superior to: The neighbors went us one better by buying two new cars.

20. had better, would be wiser or more well-advised to; ought to: We had better stay indoors today.

21. no better than one should be, Disparaging . morally inferior; immoral or amoral.

22. think better of,
     a. to reconsider and decide more favorably or wisely regarding: I was tempted to make a sarcastic retort, but thought better of it.
     b. to form a higher opinion of.