The Collaborative International Dictionary of English v.0.48:

Harmost \Har"most\ (h[aum]r"m[o^]st), n. [Gr. "armosth`s, fr.
   "armo`zein to join, arrange, command: cf. F. harmoste. See
   Harmony.] (Gr. Antiq.)
   A city governor or prefect appointed by the Spartans in the
   cities subjugated by them.
   [1913 Webster]