What does the word shaft mean?

Usage examples for shaft

  1. When it was done we withdrew to the end of the passage and looked up the shaft, and I for one was glad to see the stars shining in heaven above me. – Montezuma's Daughter by H. Rider Haggard
  2. Our thrust shaft has cracked!" – Dan Merrithew by Lawrence Perry
  3. Criticism based on any other conception of my purpose is a spent shaft. – Success (Second Edition) by Max Aitken Beaverbrook