The Collaborative International Dictionary of English v.0.48:

Intimidate \In*tim"i*date\, v. t. [imp. & p. p. Intimidated;
   p. pr. & vb. n. Intimidating.] [LL. intimidatus, p. p. of
   intimidare to frighten; pref. in- in + timidus fearful,
   timid: cf. F. intimider. See Timid.]
   To make timid or fearful; to inspire of affect with fear; to
   deter, as by threats; to dishearten; to abash.
   [1913 Webster]

         Now guilt, once harbored in the conscious breast,
         Intimidates the brave, degrades the great. --Johnson.

   Syn: To dishearten; dispirit; abash; deter; frighten;
        terrify; daunt; cow.
        [1913 Webster]

WordNet (r) 3.0 (2006):

intimidate
    v 1: make timid or fearful; "Her boss intimidates her"
    2: to compel or deter by or as if by threats [syn: intimidate,
       restrain]