The word "protoxoid" is a technical term frequently used in the field of microbiology. It refers to a genetically modified bacterial toxin that has been rendered safe for use in vaccines. The pronunciation of "protoxoid" is "proh-tuhk-soid," with stress on the second syllable. The IPA phonetic transcription for this word is /ˈprəʊtə(ʊ)ksɔɪd/. The spelling of this term can be broken down as "proto-" meaning first or initial, and "-oxoid" referring to a bacterium or bacterial toxin.
Prototoxoid.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.