What does the word doubt mean?

Usage examples for doubt

  1. Here was another of them then, no doubt! – The Belovéd Traitor by Frank L. Packard
  2. It was there that they would be, she had no doubt. – The Truants by A. E. W. (Alfred Edward Woodley) Mason
  3. I doubt I shall hear more of the matter. – The Sea-Hawk by Raphael Sabatini