Where does “Mahomedism” come from?

Mahomedism (English) comes from English Mahomed, from Arabic مُحَمَّد, from Classical Persian جَان, from Middle Persian 𐫃𐫏𐫀𐫗, from Proto-Iranian *wyaHnáH, from Proto-Indo-Iranian wyaHnás, from Proto-Indo-European h₂enh₁‑ — to breathe.

Ancestry of “Mahomedism”, step by step

Mahomedism traces back through two separate lines of ancestry.

via English Mahomed

StepLanguageWordMeaning
1EnglishMahomedthe prophet who introduced Islam
2Arabicمُحَمَّدpraised, commendable, laudable; Muhammad
3Classical Persianجَان
4Middle Persian𐫃𐫏𐫀𐫗
5Proto-Iranian*wyaHnáH
6Proto-Indo-IranianwyaHnás
7Proto-Indo-Europeanh₂enh₁‑to breathe

via English ism

StepLanguageWordMeaning
1EnglishismAn ideology, system of thought, or practice that...
2English-ismUsed to form nouns of action or process or result...
3Latin-ismus-ism
4Ancient Greek-ισμόςForms abstract nouns
5Ancient Greek-μόςForms abstract nouns
6Proto-Indo-European-mósCreates action/result nouns from verb stems
Every word from Proto-Indo-European h₂enh₁‑Every word from Proto-Indo-Iranian wyaHnásEvery word from Proto-Iranian *wyaHnáH