hanse
That part of an elliptical or many-centred arch which has the shorter radius and immediately adjoins the impost.
Now Workmen call each End of these Arches the Hanse, which Hanses are always the Arches of smaller Circles than the Scheme, which is the middle Part of these Arches, and consists of a Part of a larger Circle […]
Where it comes from
Compare French anse (“handle”), anse de panier (“surbased arch, flat arch, vault”), and English haunch (“hip”).
Adapted from the Wiktionary entry hanse (CC BY-SA 4.0).