The Collaborative International Dictionary of English v.0.48:

Credo \Cre"do\ (kr?"d?), n. [L. See Creed.]
   The creed, as sung or read in the Roman Catholic church.
   [1913 Webster]

         He repeated Aves and Credos.             --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

credo
    n 1: any system of principles or beliefs [syn: creed, credo]