Archit. [SUB- 3, 5 b.] A subsidiary or secondary arch; one of two or more arches grouped in a larger arch; the lowest member in an arch of two or more ‘orders.’
1835. R. Willis, Archit. Mid. Ages, vii. 91. The square body of the pier sustains the pier arches, while its lateral half shafts are appropriated to the sub-arches.
1849. Parker, Introd. Gothic Archit., iii. 133. Three or more lancet-lights under one arch, the points of the sub-arches touching the enclosing arch.
1879. Cassell’s Techn. Educ., III. 40. The first of the three orders, or ‘sub-arch.’
