The Collaborative International Dictionary of English v.0.48:

Excretion \Ex*cre"tion\, n. [Cf. F. excr['e]tion.]
   1. The act of excreting.
      [1913 Webster]

            To promote secretion and excretion.   --Pereira.
      [1913 Webster]

   2. That which is excreted; excrement. --Bacon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

excretion
    n 1: the bodily process of discharging waste matter [syn:
         elimination, evacuation, excretion, excreting,
         voiding]
    2: waste matter (as urine or sweat but especially feces)
       discharged from the body [syn: body waste, excretion,
       excreta, excrement, excretory product]