1833 (in Lyell), "unstratified deposit of loam," coined 1823 by German mineralogist Karl Cäsar von Leonhard (1779-1862) from German Löss "yellowish-gray soil," from Swiss German lösch (adj.) "loose" (cf. German los; see loose). Related: Loessial.
(lō'əs, lěs, lŭs) A very fine grained silt or clay, thought to have formed as the result of grinding by glaciers and to have been deposited by the wind. Most loess is believed to have originated during the Pleistocene Epoch from areas of land covered by glaciers and from desert surfaces.