phantasmagoria UK /ˌfæntæzməˈɡɒɹi.ə/US /ˌfæntæzməˈɡɔːɹi.ə/ noun3 •A dreamlike state where real and imagined elements are blurred together. •A series of events involving rapid changes in light intensity and color. •(historical) A popular 18th- and 19th-century form of theater entertainment whereby ghostly apparitions are formed. formsphantasmagorias