What does the word quaver mean?

Usage examples for quaver

  1. For reply he stood stock still, raised his nose, and emitted a long wail, a mournful, a ghastly sound, with a broken- hearted quaver at the end. – The Untamed by Max Brand
  2. Fainter grew the voice, still fainter, Sinking almost to a whisper, With a hesitating quaver, As the picture came before her Of her disappearing people. – The Legends of San Francisco by George W. Caldwell