colluvium

noun

col·​lu·​vi·​um kə-ˈlü-vē-əm 

plural colluvia kə-ˈlü-vē-ə  or colluviums

: rock detritus and soil accumulated at the foot of a slope

colluvial

kə-ˈlü-vē-əl 

adjective

Word History

Etymology

New Latin, from Medieval Latin, offscourings, alteration of Latin colluvies, from colluere to wash, from com- + lavere to wash — more at lye

First Known Use

circa 1936, in the meaning defined above