The Collaborative International Dictionary of English v.0.48:

euphoric \euphoric\ adj.
   strongly experiencing a feeling of well-being; feeling
   euphoria. Opposite of dysphoric. [Narrower terms:
   expansive]

   Syn: elated, happy.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

euphoric
    adj 1: exaggerated feeling of well-being or elation [ant:
           distressed, dysphoric, unhappy]

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "euphoric":
   accepting, at ease, beaming, blithe, blithesome, bright,
   bright and sunny, charmed, cheerful, cheery, comfortable, composed,
   content, contented, cozy, delighted, easy, easygoing, elated,
   eupeptic, exalted, exhilarated, favorably impressed with, flushed,
   genial, glad, gladsome, glowing, gratified, happy, high, hopeful,
   in clover, in good spirits, in high spirits, intrigued,
   irrepressible, laughing, of good cheer, of good comfort,
   optimistic, pleasant, pleased, pleased as Punch, pleased with,
   radiant, reconciled, resigned, riant, rosy, sanguine, sanguineous,
   sans souci, satisfied, smiling, sold on, sparkling, sunny,
   taken with, thrilled, tickled, tickled pink, tickled to death,
   uncomplaining, unrepining, winsome, without care