The spelling of "most interallied" is determined by its pronunciation. The first syllable "most" is pronounced with a long "o" sound like /moʊst/. The second syllable "inter" has the stressed syllable on the first vowel sound which is pronounced as /ˌɪn.tər/. The final syllable "allied" has a stressed long "i" sound like /əˈlaɪd/. Therefore, "most interallied" is spelled as such to ensure the correct pronunciation. This phrase means predominantly allied among different countries or groups, especially in terms of politics or military.