The interior curve of an arch.

Roget 221: interiority; inside, interior; interspace^†, subsoil, substratum; intrados.    contents etc. 190; substance, pith, marrow; backbone etc. (center) 222; heart, bosom, breast; abdomen; vitals, viscera, entrails, bowels, belly, intestines, guts, chitterings^†, womb, lap; penetralia [Lat.], recesses, innermost recesses; cave etc. (concavity) 252.    ... meer laten zien