Late Middle English; earliest use found in Guy de Chauliac's Grande Chirurgie. From post-classical Latin phlegmonosus from phlegmon + classical Latin -ōsus.
Definition of phlegmonous in US English:
phlegmonous
adjectiveˈflɛɡmənəs
Of the nature of or involving (a) phlegmon.
Origin
Late Middle English; earliest use found in Guy de Chauliac's Grande Chirurgie. From post-classical Latin phlegmonosus from phlegmon + classical Latin -ōsus.