Origin: OE. Othe, oth, ath, AS. A; akin to D. Eed, OS. E, G. Eid, Icel. Eir, Sw. Ed, Dan. Eed, Goth. Ais; cf. OIr. Oeth.
1. A solemn affirmation or declaration, made with a reverent appeal to god for the truth of what is affirmed. I have an oath in heaven An oath of secrecy for the concealing of those [inventions] which we think fit to keep secret. (bacon)
4. A careless and blasphemous use of the name of the divine being, or anything divine or sacred, by way of appeal or as a profane exclamation or ejaculation; an expression of profane swearing. A terrible oath