The Collaborative International Dictionary of English v.0.48:

Disciplinarian \Dis`ci*plin*a"ri*an\, a.
   Pertaining to discipline. "Displinarian system." --Milman.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disciplinarian \Dis`ci*plin*a"ri*an\, n.
   1. One who disciplines; one who excels in training,
      especially with training, especially with regard to order
      and obedience; one who enforces rigid discipline; a
      stickler for the observance of rules and methods of
      training; as, he is a better disciplinarian than scholar.
      [1913 Webster]

   2. A Puritan or Presbyterian; -- because of rigid adherence
      to religious or church discipline. [Obs.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

disciplinarian
    n 1: someone who demands exact conformity to rules and forms
         [syn: martinet, disciplinarian, moralist]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "disciplinarian":
   Simon Legree, absolute monarch, absolute ruler, all-powerful ruler,
   arrogator, autarch, autocrat, caesar, commissar, czar, despot,
   dictator, driver, duce, hard master, martinet, oligarch, oppressor,
   pharaoh, slave driver, stickler, taskmaster, tyrant, usurper,
   warlord