Source : WordNet®

upbeat
     adj : pleasantly (even unrealistically) optimistic [syn: {cheerful},
            {pollyannaish}]
     n 1: a contented state of being happy and healthy and prosperous;
          "the town was finally on the upbeat after our recent
          troubles" [syn: {wellbeing}, {well-being}, {welfare}, {eudaemonia},
           {eudaimonia}] [ant: {ill-being}]
     2: an unaccented beat (especially the last beat of a measure)