The spelling of the word "lightning catarrh" is quite complex. The word is pronounced as /ˈlaɪtnɪŋ kəˈtær/, with the first syllable pronounced as "light" and the second pronounced as "ning." The second word, "catarrh," is pronounced with the first syllable as "cat" and the second syllable as "arrh." The term "lightning" refers to a sudden and powerful discharge of electricity in the atmosphere, while "catarrh" is a medical condition that causes inflammation of the mucous membranes in the nose and throat. Together, the term refers to a sudden and severe bout of catarrh.
Influenza; any severe and rapidly developing coryza.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.