night soil

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Human excrement collected for use as fertilizer.

from The Century Dictionary.

• noun The contents of privies, etc. (generally removed in the night), employed as a manure.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun archaic, euphemistic Human faeces.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun human excreta used as fertilizer