"The belief that God's self-disclosure forms a progression from the O[ld ]T[estament] era to the N[ew ]T[estament] era. Hence what is known about God on the basis of Jesus Christ is more complete than what was given through the Law and the Prophets. Progressive revelation implies that the OT ought to be understood in the light of the fuller teaching found in the NT."
Stanley J. Grenz, David Guretzki, and Cherith Fee Nordling, Pocket dictionary of theological terms (Downers Grove, IL: InterVarsity Press, 1999), 96.