What does the word railing mean?

Usage examples for railing

  1. As they went, the captain leaned over the railing and laughed. – Last Words by Stephen Crane
  2. He dashed out of his little house and leaning over the railing shouted to the Ancient Mariner: Sandy, ye gomeril! – The End of the Rainbow by Marian Keith
  3. That's all very well for you to say when you know I can't climb over this railing! – The Danger Mark by Robert W. Chambers