defecation (n.)

1640s, "purification of the mind or soul" (figurative); 1650s, "act or process of separating from lees or dregs, a cleansing from impurities," from Late Latin defecationem (nominative deficatio), noun of action from past-participle stem of Latin defaecare "cleanse from dregs, purify," from the phrase de faece "from dregs" (see de- + feces). Meaning "act of evacuating the bowels" is from 1830. An Old English word for "bowel movement" was arse-gang literally "arse-going."