Swear \Swear\, v. t.

1. To utter or affirm with a solemn appeal to God for the truth of the declaration; to make (a promise, threat, or resolve) under oath.

Swear unto me here by God, that thou wilt not deal falsely with me. --Gen. xxi. 23.

He swore consent to your succession. --Shak.

2. (Law) To put to an oath; to cause to take an oath; to administer an oath to; -- ofetn followed by in or into; as, to swear witnesses; to swear a jury; to swear in an officer; he was sworn into office.

3. To declare or charge upon oath; as, he swore treason against his friend. --Johnson.

4. To appeal to by an oath.

Now, by Apollo, king, Thou swear'st thy gods in vain. --Shak.

To swear the peace against one, to make oath that one is under the actual fear of death or bodily harm from the person, in which case the person must find sureties that he will keep the peace.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Swear \Swear\, v. i. [imp. Swore, formerly Sware; p. p. Sworn; p. pr. & vb. n. Swearing.]

[OE. swerien, AS. swerian; akin to D. zweren, OS. swerian, OHG. swerien, G. schw["o]ren, Icel. sverja, Sw. sv["a]rja, Dan. sv[ae]rge, Icel. & Sw. svara to answer, Dan. svare, Dan. & Sw. svar an answer, Goth. swaran to swear, and perhaps to E. swarm. [root]177. Cf. Answer.]

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]

Source: Webster's Revised Unabridged Dictionary (1913)