1911 Encyclopædia Britannica/Slum

SLUM, a squalid, dirty street or quarter in a city, town or village, inhabited by the very poor, destitute or criminal classes; over-crowding is frequently another characteristic (see Housing). The word is a comparatively recent one and is of uncertain origin. It has been doubtfully connected with a dialectal use of “slump” in the sense of a marshy, swampy place; cf. Ger. Schlamm, mud, and Eng. dialect slammock, slattern (Skeat, Etym. Dict., 1910).