The Collaborative International Dictionary of English v.0.48:

Intrepid \In*trep"id\, a. [L. intrepidus: cf. F. intr['e]pide.
   See In- not, and Trepidation.]
   Not trembling or shaking with fear; fearless; bold; brave;
   undaunted; courageous; as, an intrepid soldier; intrepid
   spirit.

   Syn: Fearless; dauntless; resolute; brave; courageous;
        daring; valiant; heroic; doughty.
        [1913 Webster]

WordNet (r) 3.0 (2006):

intrepid
    adj 1: invulnerable to fear or intimidation; "audacious
           explorers"; "fearless reporters and photographers";
           "intrepid pioneers" [syn: audacious, brave,
           dauntless, fearless, hardy, intrepid,
           unfearing]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "intrepid":
   adventurous, audacious, bold, bold-spirited, brave, chivalric,
   chivalrous, courageous, daring, dashing, dauntless, doughty,
   fearless, gallant, game, greathearted, hardy, heroic, herolike,
   ironhearted, knightlike, knightly, lionhearted, manful, manly,
   plucky, resolute, soldierlike, soldierly, stalwart, steadfast,
   stout, stouthearted, unafraid, undaunted, valiant, valorous,
   venturesome