oathbreach
Breach or breaking of an oath; perjury.
countable, uncountable
To this list of deadly crimes, naming house-breaking, arson or fire-raising, open theft (ran), and clear murder and treason to one's lord, the Northmen seem to have added unnatural crime (arg-scap), witchcraft, blasphemy, and oath-breach, [...]
Where it comes from
From Middle English othbreche, from Old English āþbriċe, āþbryċe (“the breaking of an oath, perjury”), equivalent to oath + breach. Compare West Frisian eedbrek (“perjury”), Dutch eedbreuk (“breach of an oath”), German Low German Eedbröök (“the breach of an oath”), German Eidbruch (“the breaking of an oath”).
Adapted from the Wiktionary entry oathbreach (CC BY-SA 4.0).