Main Entry: gneiss

Pronunciation: \ˈnīs\

Function: noun

Etymology: German Gneis, alteration of Middle High German gneiste spark, from Old High German gneisto; akin to Old English fȳrgnāst spark

Date: 1757

: a foliated metamorphic rock corresponding in composition to a feldspathic plutonic rock (as granite)

— gneiss·ic \ˈnī-sik\ adjective

— gneiss·oid \-ˌsȯid\ adjective

— gneiss·ose \-ˌsōs\ adjective