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"