What does the word triad mean?

Usage examples for triad

  1. The opening of the new era was marked by the appearance of a triad of Jewesses- Grace Aguilar in England, Rachel Morpurgo in Italy, and Henriette Ottenheimer in Germany. – Jewish Literature and Other Essays by Gustav Karpeles
  2. The other member of the triad, Gaius Licinius Macer Calvus, one of the most brilliant men of his time, was too deeply plunged in politics to be more than an accomplished amateur in poetry. – Latin Literature by J. W. Mackail