dunch

From Middle English dunchen, of uncertain origin. Possibly from the noun (see below); or of North Germanic origin, related to Old Swedish diunga (“to hit, knock”), dialectal Swedish dunka (“to beat”); or from Middle English dengen, from Old English denġan, denċġan (“to knock, ding”), from Proto-Germanic *dangijaną (“to bang, knock”). Compare English dinge.

Blend of dinner +‎ lunch, probably in imitation of brunch.