What is the meaning of enough?

noun

• An adequate quantity; a quantity that is large enough to achieve a purpose.
  • usage: "enough is as good as a feast"; "there is more than a sufficiency of lawyers in this country"
  • synonyms: sufficiency

adjective

• Sufficient for the purpose.
  • usage: "an adequate income"; "the food was adequate"; "a decent wage"; "enough food"; "food enough"
  • synonyms: adequate, decent

adverb

• As much as necessary.
  • usage: "Have I eaten enough"; (`plenty' is nonstandard) "I've had plenty, thanks"
  • synonyms: plenty