loess (n.) Look up loess at Dictionary.com
1833 (in Lyell), "unstratified deposit of loam," a special use from 1823 by German mineralogist Karl Cäsar von Leonhard (1779-1862) of German Löss "yellowish-gray soil," of a type found in the Rhine valley, from Swiss German lösch (adj.) "loose" (compare German los; see loose (adj.)). Related: Loessial.