to void excrement from the bowels through the anus; have a bowel movement.
2.
to become clear of dregs, impurities, etc.
verb (used with object)
3.
to clear of dregs, impurities, etc.; purify; refine.
Origin: 1565–75; < Latin dēfaecātus (past participle of dēfaecāre to cleanse, refine), equivalent to dē-de- + faec- (stem of faex dregs, sediment) + -ātus-ate1
1570s, "to purify," from L. defæcatus, pp. of defæcare "cleanse from dregs, purify," from the phrase de fæce "from dregs," pl. fæces "feces." Excretory sense first recorded 1830 (defecation), Amer.Eng., from French.