/ əʊθ; NAmE oʊθ/ noun ( pl. oaths / əʊðz; NAmE oʊðz/)
1.
a formal promise to do sth or a formal statement that sth is true :
to take / swear an oath of allegiance
Before giving evidence, witnesses in court have to take the oath (= promise to tell the truth) .
2.
( old-fashioned ) an offensive word or phrase used to express anger, surprise, etc.; a swear word :
She heard the sound of breaking glass, followed by a muttered oath.
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IDIOMS
- on / under oath
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WORD ORIGIN
Old English āth , of Germanic origin; related to Dutch eed and German Eid .