What does the word mainmast mean?

Usage examples for mainmast

  1. " He is here," said Collins, a midshipman I had addressed, lifting up an ensign which was spread near the mainmast. – Hurricane Hurry by W.H.G. Kingston
  2. In one storm the mainmast was sprung in four places. – The Life and Voyages of Christopher Columbus (Vol. II) by Washington Irving