Definition of oath
1a(1) : a solemn usually formal calling upon God or a god to witness to the truth of what one says or to witness that one sincerely intends to do what one says
(2) : a solemn attestation of the truth or inviolability of one's words
The witness took an oath to tell the truth in court.
b : something (such as a promise) corroborated by an oath
They were required to swear an oath of loyalty. took the oath of office
2 : an irreverent or careless use of a sacred name broadly : swear word He uttered an oath and stormed away.
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Time Traveler for oath
The first known use of oath was before the 12th century
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