The word "undulant creosoti salicylatum extensum" is a compound medical term consisting of several root words. The spelling of each component reflects its pronunciation based on International Phonetic Alphabet (IPA) symbols. "Undulant" is pronounced as /ˈʌn djʊl ənt/, "creosoti" as /kriːˈɒs ə ti/, "salicylatum" as /ˌsæl ɪˈsaɪl ə təm/, and "extensum" as /ɪkˈstɛns əm/. Together, the term describes a condition characterized by undulating fever and inflammation of the joints and muscles, treated with an extended-release version of a medication containing creosote and salicylic acid.
Creosote-salicylic acid salve mull, mulla creosoti salicylata (N.F.).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.