concave arch

They looked like overgrown bushes, about six feet high, and the lower branches formed a concave arch.

It was also described as having hind legs with five-toed horseshoe-shaped feet with concave arches - which appeared to be suited for bipedal locomotion - but no forelimbs.

Perceptively, Denby had recognized that "the airiness of both house and lobby derive from the proportions of the proscenium," originally formed by concave arches of gold filigree.

Our engines shrieked as I forced Wooden Shoe into impossible twists along the underside of engineering, skimming the sensor dish in a concave arch and surfacing directly on the starboard phaser pod.