dung (n.) Look up dung at Dictionary.com
Old English dung "manure, fertilizer," common Germanic (cognates: Old Frisian and Old Saxon dung "manure;" Old High German tunga "manuring," tung "underground room covered with manure;" German Dung; Old Norse dyngja "heap of manure, women's apartment; Swedish dynga "dung, muck;" Danish dynge "heap, mass, pile"), perhaps from a PIE *dhengh- "covering" (cognates: Lithuanian dengti "to cover," Old Irish dingim "I press").

The word recalls the ancient Germanic custom (reported by Tacitus) of covering underground shelters with manure to keep in warmth in winter. The meaning "animal excrement," whether used as fertilizer or not, is from late 13c.
The whole body of journeymen tailors is divided into two classes, denominated Flints and Dungs: the former work by the day and receive all equal wages; the latter work generally by the piece [1824].
Dung beetle attested by 1630s. In colloquial American English, tumble-bug. An Old English word for it was tordwifel "turd weevil."