Meaning of tetrarch

te•trarch

Pronunciation: (te'trärk, tē'-), [key]
— n.
  1. any ruler of a fourth part, division, etc.
  2. a subordinate ruler.
  3. one of four joint rulers or chiefs.
  4. the ruler of the fourth part of a country or province in the ancient Roman Empire.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.