Webster's Revised Unabridged Dictionary · 1913

(Medicine) A dry slough, crust, or scab, which separates from the healthy part of the body, as that produced by a burn, or the application of caustics.

(Geology) In Ireland, one of the continuous mounds or ridges of gravelly and sandy drift which extend for many miles over the surface of the country, deposited by streams in meltwater channels under glaciers. Similar ridges in Scotland are called kames or kams. The spelling form esker is now the most commonly used, and the term is applied in geology to similar ridges created by glaciers anywhere in the world. Eskers vary in size and extent, but can be 100 feet high and up to 100 miles long.