The Collaborative International Dictionary of English v.0.48:

bacteriostatic \bacteriostatic\ adj.
   1. of or pertaining to bacteriostasis or a bacteriostat.
      [WordNet 1.5]

   2. causing bacteriostasis; -- said of chemical substances,
      such as certain antibacterial agents.
      [PJC]

   Note: Substances, such as antibiotics, which inhibit
         bacterial growth are usually classified as
         bacteriostatic or bacteriocidal depending on the rate
         at which bacteria exposed to the agents[4] die. The
         rates of death of bacteria exposed to antibacterial
         agents[4] are, however, dependent on the concentration
         of the agent[4], and form a continuum with some
         antibacterial agents[4] of intermediate type. The
         penicillins are considered as typical bactericidal
         agents, and chloramphenicol or the sulfa drugs as
         typical bacteriostatic agents. In general, inhibitors
         of cell-wall synthesis will be bactericidal and many
         inhibitors of protein synthesis are classed as
         bacteriostatic, but some of the aminoglycosides also
         kill bacteria rapidly.
         [PJC]

WordNet (r) 3.0 (2006):

bacteriostatic
    adj 1: of or relating to or causing bacteriostasis