Swear v. i. [imp. Swore formerly Sware p. p. Sworn p. pr. & vb. n. Swearing.]
1. To affirm or utter a solemn declaration, with an appeal to God for the truth of what is affirmed; to make a promise, threat, or resolve on oath; also, to affirm solemnly by some sacred object, or one regarded as sacred, as the Bible, the Koran, etc.
Ye shall swear by my name falsely. --Lev. xix. 12.
I swear by all the Roman gods. --Shak.
2. Law To give evidence on oath; as, to swear to the truth of a statement; he swore against the prisoner.
3. To make an appeal to God in an irreverant manner; to use the name of God or sacred things profanely; to call upon God in imprecation; to curse.
[I] swore little; diced not above seven times a week. --Shak.
To swear by, to place great confidence in a person or thing; to trust implicitly as an authority. “I simply meant to ask if you are one of those who swear by Lord Verulam.” --Miss Edgeworth.
To swear off, to make a solemn vow, or a serious resolution, to abstain from something; as, to swear off smoking. [Slang]