The Collaborative International Dictionary of English v.0.48:

Invigorate \In*vig"or*ate\ ([i^]n*v[i^]g"[~e]r*[=a]t), v. t.
   [imp. & p. p. Invigorated ([i^]n*v[i^]g"[~e]r*[=a]`t[e^]d);
   p. pr. & vb. n. Invigorating.] [Pref. in- in + vigor.]
   To give vigor to; to strengthen; to animate; to give life and
   energy to.
   [1913 Webster]

         Christian graces and virtues they can not be, unless
         fed, invigorated, and animated by universal charity.
                                                  --Atterbury.

   Syn: To refresh; animate; exhilarate; stimulate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

invigorating
    adj 1: imparting strength and vitality; "the invigorating
           mountain air" [ant: debilitating]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "invigorating":
   activating, analeptic, animating, animative, beneficial, benign,
   bracing, brisk, cheerful, cheering, cheery, chill, chilly,
   constitutional, cool, coolish, cordial, corroborant, crisp, crispy,
   encouraging, energizing, enlivening, exhilarating, exhilarative,
   fresh, glad, gladdening, good, good for, health-enhancing,
   health-preserving, healthful, healthy, heart-warming, heartening,
   hygeian, hygienic, inspiring, inspiriting, invigorative, joyful,
   quickening, refreshful, refreshing, regaling, rejuvenating,
   restorative, reviving, roborant, rousing, salubrious, salutary,
   sanitary, stimulating, stimulative, strengthening, temperate,
   tonic, viable, vitalizing, vivifying, wholesome, zestful, zesty