The Collaborative International Dictionary of English v.0.48:

abs \abs\ ([a^]bz), n. pl. (Anat.)
   The abductor muscles of the stomach; -- a contraction used by
   body-building and health enthusiasts. Used similarly to
   pecs and delts.
   [PJC]

WordNet (r) 3.0 (2006):

ABS
    n 1: any of a class of composite plastics used to make car
         bodies and cases for computers and other appliances [syn:
         acrylonitrile-butadiene-styrene, ABS]