What does the word thirty mean?

Usage examples for thirty

  1. Don't forget, dear, I'm only just thirty. – The Heather-Moon by C. N. Williamson and A. M. Williamson
  2. As for the car- our bully old Thirty- well, we'll have to get home without it. – The Auto Boys' Mystery by James A. Braden
  3. Why, he must be thirty. – My Little Sister by Elizabeth Robins