Ogive

An ogive (/ˈoʊdʒaɪv/ OH-jyv) is the roundly tapered end of a two-dimensional or three-dimensional object.

Villard de Honnecourt, a 13th-century itinerant master-builder from the Picardy in the north of France, was the first writer to use the word ogive. The OED considers the French term's origin obscure; it might come from the Late Latin obviata, the feminine perfect passive participle of obviare, meaning the one who has met or encountered the other.