Osaka UK /əʊˈsɑːkə/US /oʊˈsɑːkə/ noun2 •The capital city of Osaka Prefecture, Japan.And Osaka comes alive in the warm months of summer and fall as the locals take to their outdoor restaurants, flock to festivals and cheer on the hometown baseball team, the Hanshin Tigers. — 2005 •A prefecture on the island of Honshū, Japan. formsOsakas