The correct spelling of this word is "siphonophore." It is a type of marine organism that consists of a colony of specialized individuals called zooids. The word is pronounced /ˈsaɪfənəfɔːr/ (SIGH-fə-nə-for) using IPA phonetic transcription. The spelling "syphionthus" is incorrect and may result from confusion or misspelling. Correct spelling is crucial to ensure that the information conveyed is accurate and easily understood.
Syphilionthus.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.