1. Law, the substitution of a new obligation for an old one, usually by the substitution of a new debtor or of a new creditor. 2. the introduction of something new; innovation. [1525–35; < L novātiōn– (s. of novātiō) a renewing, equiv. to novāi(us) (ptp. of novāre to renew, deriv. of novus NEW...