ichthyologyPronunciation: /ˌɪkθɪˈɒlədʒi/Definition of ichthyology noun [mass noun] the branch of zoology that deals with fishes. Derivatives ichthyologicalPronunciation: /-əˈlɒdʒɪk(ə)l/ adjective ichthyologist noun ichthyology in other Oxford dictionaries Definition of ichthyology in the US English dictionary