to hold oneself back voluntarily, especially from something regarded as improper or unhealthy (usually followed by from): to abstain from eating meat.
2.
to refrain from casting one's vote: a referendum in which two delegates abstained.
Origin: 1350–1400; Middle English abste(i)nen < Middle French abstenir ≪ Latin abstinēre, equivalent to abs-abs- + -tinēre, combining form of tenēre to hold, keep
late 14c., "to withhold oneself," from O.Fr. abstenir, from L. abstinere "withhold," from ab(s)- "from, away from" + tenere "to hold" (see tenet). Specifically of liquor, attested from late 14c. Of voting, 1885.