noun Jo·han·nes [yoh-hah-nuh s] /yoʊˈhɑ nəs/. Okeghem, Jean d'. noun Johannes (joːˈhɑnəs), Jean d' (ʒɑ̃ d), or Jan van (jɑn vɑn). ?1430–?95, Flemish composerAlso: Ockenheim (ˈɒkənˌhaɪm)