What does the word combination mean?

Usage examples for combination

  1. There is another safe, of which I hold the combination. – Three Thousand Dollars by Anna Katharine Green
  2. Even in heraldry the combination he beheld would have been a strange one. – Warlock o' Glenwarlock by George MacDonald
  3. The combination of advance warning of eruption, a nuclear explosion, and the eruption itself provided data never before obtainable. – The Flaming Mountain by Harold Leland Goodwin