Archit. Obs. rare. In 8 sommer. [Back-formation from SUMMERING vbl. sb.2] intr. To radiate from or converge towards a center, like the joints of an arch.
1703. Moxon, Mech. Exerc., 279. Let the breadth of the upper part of the Keystone be the height of the Arch, viz. 14 Inches, and Sommer, from the Centre at I.
1703. T. N., City & C. Purchaser, 9. The Key-stone … ought to … Sommer (or point with its 2 edges) to the Centre.
