The Collaborative International Dictionary of English v.0.48:

Codify \Co"di*fy\ (? or ?; 277), v. t. [imp. & p. p. Codified;
   p. pr. & vb. n. Codifying.] [Code + -fy: cf. F. codifier.]
   To reduce to a code, as laws.
   [1913 Webster]

WordNet (r) 3.0 (2006):

codify
    v 1: organize into a code or system, such as a body of law;
         "Hammurabi codified the laws"