The Collaborative International Dictionary of English v.0.48:

Levo- \Le"vo-\ (l[=e]"v[-o]-) pref.
   A prefix from L. laevus, meaning:
   (a) Pertaining to, or toward, the left; as, levorotatory.
   (b) (Chem. & Opt.) Turning the plane of polarized light to
       the left; as, levotartaric acid; levoracemic acid;
       levogyratory crystals, etc. [Written also l[ae]vo-.]
       [1913 Webster]