vexillologyPronunciation: /ˌvɛksɪˈlɒlədʒi/Definition of vexillology noun [mass noun] the study of flags. Derivatives vexillologicalPronunciation: /-ləˈlɒdʒɪk(ə)l/ adjective vexillologist noun Origin: 1950s: from Latin vexillum 'flag' + -logyvexillology in other Oxford dictionaries Definition of vexillology in the US English dictionary