The Collaborative International Dictionary of English v.0.48:

Res \Res\ (r?z), n.; pl. Res. [L.]
   A thing; the particular thing; a matter; a point.
   [1913 Webster]

   Res gestae [L., things done] (Law), the facts which form
      the environment of a litigated issue. --Wharton.

   Res judicata [L.] (Law), a thing adjudicated; a matter no
      longer open to controversy.
      [1913 Webster]

WordNet (r) 3.0 (2006):

RES
    n 1: a widely distributed system consisting of all the cells
         able to ingest bacteria or colloidal particles etc, except
         for certain white blood cells [syn: reticuloendothelial
         system, RES]

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

RES
       Remote Entry Services


Bouvier's Law Dictionary, Revised 6th Ed (1856):

RES, property. Things. The terms "Res," "Bona," "Biens," used by jurists who
have written in the Latin and French languages, are intended to include
movable or personal, as well as immovable or real property. 1 Burge, Confl.
of Laws, 19. See Biens; Bona; Things.