The Collaborative International Dictionary of English v.0.48:

Conviviality \Con*viv`i*al"i*ty\, n.; pl. Convivialities.
   The good humor or mirth indulged in upon festive occasions; a
   convivial spirit or humor; festivity.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conviviality
    n 1: a jovial nature [syn: conviviality, joviality]
    2: a boisterous celebration; a merry festivity [syn:
       merrymaking, conviviality, jollification]