fiesta UK /fɪˈestə/US /fiˈɛstə/noun 2verb 1forms 3 noun2 •A religious festival. •A festive occasion.Runners being chased by bulls during the San Fermin bull-running festival in Pamplona: But long working hours mean it's not all fiestas in Spain. — 2011 verb1 •To take part in a festive celebration; to party.We're going to party, karamu, fiesta, forever — 1983 formsfiestaed · fiestaing · fiestas