The Collaborative International Dictionary of English v.0.48:

Systemic \Sys*tem"ic\, a.
   1. Of or relating to a system; common to a system; as, the
      systemic circulation of the blood.
      [1913 Webster]

   2. (Anat. & Physiol.) Of or pertaining to the general system,
      or the body as a whole; as, systemic death, in distinction
      from local death; systemic circulation, in distinction
      from pulmonic circulation; systemic diseases.
      [1913 Webster]

   Systemic death. See the Note under Death, n., 1.
      [1913 Webster]

WordNet (r) 3.0 (2006):

systemic
    adj 1: affecting an entire system; "a systemic poison"

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "systemic":
   acaricide, anthelmintic, antibiotic, antiseptic, bug bomb,
   carbamate insecticide, chemosterilant,
   chlorinated hydrocarbon insecticide, contact poison, defoliant,
   disinfectant, eradicant, fumigant, fungicide, germicide, herbicide,
   insect powder, insecticide, microbicide, miticide,
   organic chlorine, organic phosphate insecticide, pesticide, poison,
   rat poison, roach paste, roach powder, rodenticide, stomach poison,
   systemic insecticide, toxic, toxicant, toxin, venin, venom,
   vermicide, virus, weed killer