DR

from The Collaborative International Dictionary of English v.0.48

Dr \Dr.\ n.
   abbreviation for {doctor}, a title accorded to a person who
   holds a doctorate degree from an academic institution, such
   as a Ph.D. degree or M.D. degree. [abbrev.]

   Syn: doctor.
        [WordNet 1.5]

   2. a licensed doctor of medicine.

   Syn: doctor, doc, physician, MD, medico.
        [WordNet 1.5]

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

DR
       Developer Release (Linux, Apple, ...)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

DR
       Designated Router (PIM, Multicast)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

DR
       Digital Research (manufacturer)