: a formal and serious promise to tell the truth or to do something
: an offensive or rude word that is used to express anger, frustration, surprise, etc.
Full Definition of OATH
a (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
b: something (as a promise) corroborated by an oath
: an irreverent or careless use of a sacred name; broadly:swearword