WordNet sense 1 (the quality of being cheerful and dispelling gloom):

cheerfulness, sunniness, sunshine

WordNet sense 2 (give encouragement to):

embolden, hearten, recreate, recreate

WordNet sense 3 (cause (somebody) to feel happier or more cheerful):

jolly along, jolly up, cheer up

WordNet sense 4 (become cheerful):

chirk up

WordNet sense 5 (urge on or encourage especially by shouts):

barrack, exhort, inspire, urge, pep up, urge on