What does the word pentagon mean?

Usage examples for pentagon

  1. When I called the Pentagon, they admitted this much, and that was all. – The Flying Saucers are Real by Donald Keyhoe
  2. But it hadn't yet been decided by the Pentagon whether the Space Exploration Project would be taken over by the Army or the Navy or the Air Corps, so Joe wore no insignia of rank. – Space Tug by Murray Leinster
  3. Temple was a thermo- nuclear engineer with more military secrets buzzing around inside his head than in a warehouse of burned Pentagon files. – Voyage To Eternity by Milton Lesser