"to throw out or eliminate," specifically "to eliminate from an body by a process of secretion and discharge," 1610s, from Latin excretus, past participle of excernere "to sift out, discharge," from ex "out" (see ex-) + cernere "sift, separate" (from PIE root *krei- "to sieve," thus "discriminate, distinguish"). Related: Excreted; excreting.

"pertaining to excretion," 1680s, from excrete + -ory.

"trivial talk, nonsense," 1865, American English, probably from Dutch dialect pappekak, from Middle Dutch pappe "soft food" (see pap) + kak "dung," from Latin cacare "to excrete" (from PIE root *kakka- "to defecate").