Enough?

What is meant by Enough?

Sometimes Im really confused with this word...how much is enough and how is not?

Lets say about study,
studying syllabus is enough? of course we will get a NO for this question.
But then how much is enough? when will it be TRUE? Is this possible?

Says about earnings,
same question with different subject here. Enough to survive is enough? or else how much?


ps Eric: I saw yur msg in the box but i dont have time to complete that tag recently.