An "oath" is a solemn promise or declaration, often invoking a divine witness to the truth of what someone is saying or the commitment they are making. Oaths are commonly used in legal or formal contexts, such as when someone testifies in court or takes a position of responsibility, to signify that they will uphold their duties and tell the truth.
The word "oath" comes from the Old English "āþ," which means a promise or an oath. This word is related to the German "eid" and the Dutch "eed," all deriving from the Proto-Germanic "*aiþaz," which means "to dare." The roots of the word emphasize the seriousness and commitment that come with making an oath.