diptote

[ dip-toht ]
/ ˈdɪp toʊt /

noun

a substantive declined in only two cases, especially when occurring in a language in which this is less than the normal number.

Origin of diptote

1605–15; < Late Latin diptōtos noun with only two cases < Greek, equivalent to di- di-1 + -ptōtos, verbid of píptein to fall; compare ptōsis accidence, literally, falling