Mid 19th century; earliest use found in George Phillips (1804–1892), orientalist. Originally apparently shortened from plusquamperfect, probably after pluperfect. In later use perhaps from plus + perfect, after pluperfect.
Definition of plusperfect in US English:
plusperfect
nounˌplʌsˈpəːfɪkt
Grammar rare
Pluperfect.
Origin
Mid 19th century; earliest use found in George Phillips (1804–1892), orientalist. Originally apparently shortened from plusquamperfect, probably after pluperfect. In later use perhaps from plus + perfect, after pluperfect.