orthopnea
noun
or·thop·nea
variants:
or chiefly British orthopnoea \ ȯr-ˈthäp-nē-ə also ˌȯr-ˌthäp-ˈnē-ə \
Medical Definition of orthopnea
: difficulty in breathing that occurs when lying down and is relieved upon changing to an upright position (as in congestive heart failure)