The Collaborative International Dictionary of English v.0.48:

Abstain \Ab*stain"\, v. t.
   To hinder; to withhold.
   [1913 Webster]

         Whether he abstain men from marrying.    --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Abstain \Ab*stain"\, v. i. [imp. & p. p. Abstained; p. pr. &
   vb. n. Abstaining.] [OE. absteynen, abstenen, OF. astenir,
   abstenir, F. abstenir, fr. L. abstinere, abstentum, v. t. &
   v. i., to keep from; ab, abs + tenere to hold. See
   Tenable.]
   To hold one's self aloof; to forbear or refrain voluntarily,
   and especially from an indulgence of the passions or
   appetites; -- with from.
   [1913 Webster]

         Not a few abstained from voting.         --Macaulay.
   [1913 Webster]

         Who abstains from meat that is not gaunt? --Shak.
   [1913 Webster]

   Syn: To refrain; forbear; withhold; deny one's self; give up;
        relinquish.
        [1913 Webster]

WordNet (r) 3.0 (2006):

abstain
    v 1: refrain from voting
    2: choose not to consume; "I abstain from alcohol" [syn:
       abstain, refrain, desist] [ant: consume, have,
       ingest, take, take in]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "abstain":
   abnegate, abstain from, avoid, constrain, cop out, curb, decline,
   dispense with, do without, duck the issue, eschew, evade,
   evade the issue, forbear, forgo, hold, hold aloof from, hold back,
   hold off, keep, keep back, keep from, keep in hand, let alone,
   let go by, never touch, not touch, not use, pass up, refrain,
   refrain from, refuse, reject, reserve, save, shun, sit it out,
   spare, spurn, stand aloof from, stand neuter, straddle, trim,
   waive, withhold