The spelling of the word "combustious" can be quite confusing. In IPA phonetic transcription, it would be spelled as /kəmˈbʌs.tjʊs/. The "u" after the "m" is pronounced as a short "u" sound, similar to the "u" in "umbrella". The "tj" sound is also important to note, as it is a combination of the "t" and "j" sounds, and is similar to the "ch" sound in "cheese". Despite its challenging spelling, "combustious" simply means "combustible" or "flammable".