Orthopnoea \Or`thop*n[oe]"a\, Orthopny \Or*thop"ny\, n. [L.
orthopnoea, Gr. ?; 'orqo`sstraight, right + pnei^n to
breathe: cf. F. orthopn['e]e.] (Med.)
Specifically, a morbid condition in which respiration can be
performed only in an erect posture; by extension, any
difficulty of breathing.
[1913 Webster]