[ yoo-jee-oh-sing-klahyn, -sin- ]
/ yuˌdʒi oʊˈsɪŋ klaɪn, -ˈsɪn- /

noun Geology.

a former marine zone, bordering an ocean basin, marked by very thick deposits of sediment in which the products of volcanic activity are associated with clastic sediments.

Origin of eugeosyncline

First recorded in 1940–45; eu- + geosyncline
Related formseu·ge·o·syn·cli·nal, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019