What does the word extra mean?

Usage examples for extra

  1. How he must have hurried to reach his tree when the acorn was extra large! – The Woodpeckers by Fannie Hardy Eckstorm
  2. He put up the extra $ 500. I said to him, " You know you must turn over the baby card the first time, or you lose." – Forty Years a Gambler on the Mississippi by George H. Devol
  3. The extra value which comes from the money functions rests chiefly in its superior saleability. – The Value of Money by Benjamin M. Anderson, Jr.