Source : Webster's Revised Unabridged Dictionary (1913)

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.

         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.

Source : WordNet®

intimidating
     adj : discouraging through fear [syn: {daunting}]