Divine Rank is used to measure the relative strengths of D&D deities. The acronym DVR has been suggested because DR already means something else in D&D terms, that of damage reduction.
As far as I'm aware, a deity with a divine rank of over 20 (21+, in other words) is referred to as a greater deity, the highest rank it is possible to achieve within D&D terms.
Edit: Seems I was mistaken.
From the SRD:
These entities are beyond the ken of mortals and care nothing for worshipers. They do not grant spells, do not answer prayers, and do not respond to queries. If they are known at all, it is to a handful of scholars on the Material Plane. They are called overdeities. In some pantheistic systems, the consent of an overdeity is required to become a god.
Am I the only one who is slightly miffed that the new thread title doesn't have some catchy acronym? I suggest something like The Giant Online Author's Transcribed Sayings, just so we can refer all newcomers to The GOATS in the future