early 15c., abjuren, "renounce on oath, repudiate, forswear," originally especially "renounce or recant (a heresy) on oath," from Old French abjurer and directly from Latin abiurare "deny on oath," from ab "off, away from" (see ab-) + iurare "to swear," from ius (genitive iuris) "law" (see jurist). Related: Abjured; abjuring.