The Collaborative International Dictionary of English v.0.48:

Govern \Gov"ern\, v. t. [imp. & p. p. Governed; p. pr. & vb.
   n. Governing.] [OF. governer, F. gouverner, fr. L.
   gubernare to steer, pilot, govern, Gr. kyberna^n. Cf.
   Gubernatorial.]
   1. To direct and control, as the actions or conduct of men,
      either by established laws or by arbitrary will; to
      regulate by authority. "Fit to govern and rule
      multitudes." --Shak.
      [1913 Webster]

   2. To regulate; to influence; to direct; to restrain; to
      manage; as, to govern the life; to govern a horse.
      [1913 Webster]

            Govern well thy appetite.             --Milton.
      [1913 Webster]

   3. (Gram.) To require to be in a particular case; as, a
      transitive verb governs a noun in the objective case; or
      to require (a particular case); as, a transitive verb
      governs the objective case.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Govern \Gov"ern\, v. i.
   To exercise authority; to administer the laws; to have the
   control. --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

govern
    v 1: bring into conformity with rules or principles or usage;
         impose regulations; "We cannot regulate the way people
         dress"; "This town likes to regulate" [syn: regulate,
         regularize, regularise, order, govern] [ant:
         deregulate]
    2: direct or strongly influence the behavior of; "His belief in
       God governs his conduct"
    3: exercise authority over; as of nations; "Who is governing the
       country now?" [syn: govern, rule]
    4: require to be in a certain grammatical case, voice, or mood;
       "most transitive verbs govern the accusative case in German"

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "govern":
   administer, administrate, arrest, be master, be responsible for,
   boss, bridle, call the shots, call the signals, captain,
   carry authority, carry on, carry out, chair, check, command,
   conduct, constrain, contain, control, cool, cool off,
   crack the whip, curb, curtail, decelerate, decide, determine,
   direct, discipline, dispose, dominate, dompt, engineer, enjoin,
   execute, guard, guide, handle, have clout, have power,
   have the power, have the right, have the say, head, head up,
   hinder, hold, hold at bay, hold back, hold fast, hold in,
   hold in check, hold in leash, hold the reins, hold up, inhibit,
   keep, keep back, keep from, keep in, keep in check,
   keep under control, lay under restraint, lead, lead on, look after,
   make the rules, manage, maneuver, manipulate, master, mastermind,
   officer, order, overrule, oversee, pilot, possess authority,
   prescribe, preside over, prohibit, pull, pull in, pull the strings,
   quarterback, regulate, reign, rein, rein in, render, repress,
   restrain, retard, retrench, rule, run, set back, shepherd, skipper,
   slow down, snub, stand over, steer, straiten, subdue, superintend,
   supervise, suppress, sway, take command, take the lead,
   wear the crown, wear the pants, wield authority, withhold