The Collaborative International Dictionary of English v.0.48:

Dominate \Dom"i*nate\, v. t. [imp. & p. p. Dominated; p. pr. &
   vb. n. Dominating.] [L. dominatus, p. p. of dominari to
   dominate, fr. dominus master, lord. See Dame, and cf.
   Domineer.]
   To predominate over; to rule; to govern. "A city dominated by
   the ax." --Dickens.
   [1913 Webster]

         We everywhere meet with Slavonian nations either
         dominant or dominated.                   --W. Tooke.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dominate \Dom"i*nate\, v. i.
   To be dominant. --Hallam.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dominate
    v 1: be larger in number, quantity, power, status or importance;
         "Money reigns supreme here"; "Hispanics predominate in this
         neighborhood" [syn: predominate, dominate, rule,
         reign, prevail]
    2: be in control; "Her husband completely dominates her"
    3: have dominance or the power to defeat over; "Her pain
       completely mastered her"; "The methods can master the
       problems" [syn: dominate, master]
    4: be greater in significance than; "the tragedy overshadowed
       the couple's happiness" [syn: overshadow, dominate,
       eclipse]
    5: look down on; "The villa dominates the town" [syn:
       dominate, command, overlook, overtop]