Correct spelling for the English word "most expeditive" is [mˈə͡ʊst ˈɛkspədɪtˌɪv], [mˈəʊst ˈɛkspədɪtˌɪv], [m_ˈəʊ_s_t ˈɛ_k_s_p_ə_d_ɪ_t_ˌɪ_v] (IPA phonetic alphabet).
The word "expeditive" does not have a well-established etymology as it is not commonly used or recognized in modern English. It seems to be a derivative of the word "expedite", which comes from the Latin word "expeditus" meaning "unimpeded" or "ready for action". "Expedite" entered English in the early 17th century and originally meant "to extricate" or "to set free". Over time, its meaning evolved to "to quicken" or "to accelerate". However, "most expeditive" is not a common phrase in contemporary English, so its precise etymology is unclear.