/æbˈdʒʊər/
[verb] To formally and seriously promise to give up a belief, a habit, or a way of life, often in public. It suggests a strong and final rejection, not just a casual change of mind.
To abjure something is literally to swear it away — the word carries the weight of an oath in every syllable.
At the heart of 'abjure' is the Latin verb 'jurare', meaning 'to swear' or 'to take an oath'. This root is ancient and powerful, connected to the Latin word 'jus' (meaning 'law' or 'right'), which gave Rome its entire legal vocabulary. From 'jurare', Latin built the compound verb 'abjurare' by attaching the prefix 'ab-', meaning 'away' or 'away from'. So 'abjurare' meant, quite literally, 'to swear away' — to remove something from yourself through the solemn force of an oath.
The word passed from Classical Latin into Medieval Latin, where it was used extensively in legal and ecclesiastical contexts. Church courts and secular tribunals both relied on formal oaths, and 'abjurare' described the specific act of renouncing a belief or allegiance under oath. This was not a private decision but a public performance — a moment in front of witnesses where a person declared, formally and irrevocably, that they were cutting ties with something they had previously held or done.
English borrowed the word in the 15th century, most likely directly from Medieval Latin or from the Old French 'abjurer', which had itself taken the word from Latin. The chain runs: Latin 'abjurare' → Old French 'abjurer' → Middle English 'abjuren'. At this point in English history, the word carried its full legal and religious weight. Heretics were famously required to abjure their false beliefs before a court or congregation; to abjure was to publicly and formally recant, often under considerable pressure.
One of the most famous historical uses involves Galileo, who in 1633 was compelled by the Roman Inquisition to abjure his belief that the Earth moved around the Sun. Whether he muttered 'and yet it moves' under his breath afterward is almost certainly legend, but the abjuration itself was real, documented, and devastating. The word thus carries in its history some of the most dramatic moments of intellectual and religious conflict in Western civilization.
Over time, 'abjure' softened slightly in everyday English usage. While it still suggests a serious and deliberate renunciation, it no longer requires an actual oath or a formal legal setting. A person might today 'abjure' violence, or 'abjure' a bad habit, meaning simply that they firmly and completely reject it. The solemnity remains, however — 'abjure' is never a casual word. Its near-synonym 'forswear' follows a parallel path, built from Old English 'swerian' (to swear) with the prefix 'for-' (away), showing how both Germanic and Latin traditions reached for the same metaphor: that giving something up completely feels like swearing it out of your life.
The family of words descended from Latin 'jurare' is remarkably large in English. Latin 'jurare' → Old French 'jurer' → English 'jury'; Latin 'juramentum' → Old French 'serment' → English 'swear' (by semantic influence); Latin 'perjurare' → Old French 'parjurer' → English 'perjure'; and Latin 'jurare' directly into English 'adjure' (to urge solemnly), 'conjure' (originally to swear together), and 'injure' (via 'injuria', a wrong against the law). Each of these words carries a ghost of that original Roman courtroom, where words spoken under oath had the weight of law.