The Collaborative International Dictionary of English v.0.48:

Excrete \Ex*crete"\, v. t. [imp. & p. p. Excreted; p. pr. &
   vb. n. Excreting.] [L. excretus, p. p. of excernere to sift
   out, discharge; ex out + cernere to sift, separate. See
   Crisis.]
   To separate and throw off; to excrete urine. "The mucus thus
   excreted." --Hooper.
   [1913 Webster]