Definition of Pentagonian in US English:

Pentagonian

adjective

  • Chiefly US. Of or relating to the Pentagon, or the United States Department of Defense; characteristic of the Pentagon or its occupants.

noun

  • Chiefly US. A person who works for the United States Department of Defense (in the Pentagon).

Origin

Late 16th century (in an earlier sense). From pentagon + -ian.

Pronunciation

Pentagonian

/ˌpɛntəˈɡəʊnɪən/