What is the meaning of maximum?

noun

• The largest possible quantity.
  • synonyms: upper limit
• The greatest possible degree.
  • usage: "he tried his utmost"
  • synonyms: utmost, uttermost, level best
• The point on a curve where the tangent changes from positive on the left to negative on the right.

adjective

• The greatest or most complete or best possible.
  • usage: "maximal expansion"; "maximum pressure"
  • synonyms: maximal