Lewis & Short

chīlĭarchēs, ae, or chīlĭarchus, i, m., = χιλιάρχης or χιλίαρχος,

  1. I. a commander of 1000 soldiers, a chiliarch, Curt. 5. 2, 2. Also in gen., a head of 1000 persons, Cod. Th. 16, 10, 20, § 4.
  2. II. Among the Persians, the highest officer of state next to the king, chancellor of state, Nep. Con. 3, 2.