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]

WordNet (r) 3.0 (2006):

Dr.
    n 1: a person who holds Ph.D. degree (or the equivalent) from an
         academic institution; "she is a doctor of philosophy in
         physics" [syn: doctor, Dr.]
    2: a licensed medical practitioner; "I felt so bad I went to see
       my doctor" [syn: doctor, doc, physician, MD, Dr.,
       medico]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DR
       Designated Router (PIM, Multicast)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

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


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DR
       Digital Research (manufacturer)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DR
       Dynamic Reconfiguration (Solaris, Sun)