dome

Dome comes from Middle French dome, domme, from Italian duomo, which traces to Latin domus (ecclesiae), literally "house (of the church)." That Latin phrase was itself a calque of the Ancient Greek oîkos tês ekklēsías, "house of the assembly."

The phrase for a church building narrowed over time into a word for the rounded roof that came to define such churches, eventually standing for the shape itself rather than the whole structure.

Dome is a doublet of both domus and duomo, meaning all three ultimately descend from the same Latin root but arrived in English through different paths.