oath

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A solemn, formal declaration or promise to fulfill a pledge, often calling on God, a god, or a sacred object as witness.
• noun The words or formula of such a declaration or promise.
• noun Something declared or promised.
• noun An irreverent or blasphemous use of the name of God or something held sacred.
• noun An imprecation; a curse.
• idiom (take an oath) To agree to a pledge of truthfulness or faithful performance.
• idiom (under oath) Under a burden or responsibility to speak truthfully or perform an action faithfully.

from The Century Dictionary.

• To make to take an oath; put to the oath.
• To use as an oath; swear by.
• To call, speak to, or curse with an oath.
• To swear; use oaths.
• noun A solemn appeal to the Supreme Being in attestation of the truth of some statement or the binding character of some covenant, undertaking, or promise; an outward pledge that one's testimony or promise is given under an immediate sense of responsibility to God.
• noun The form of words in which such attestation is made.
• noun A light or blasphemous use of the name of the Divine Being, or of anything associated with the more sacred matters of religion, by way of appeal, imprecation, or ejaculation.
• noun Loosely — An ejaculation similar in form to an oath, but in which the name of God or of anything sacred is not used.
• noun An imprecation, differing from a curse in its less formal and more exclamatory character: it may be humorous, or even affectionate, among rude and free-living men.
• noun An exclamatory word or phrase, usually without appropriateness to the subject in hand, expressing surprise, and generally displeasure, though sometimes even approval or admiration.

from the GNU version of the Collaborative International Dictionary of English.

• noun A solemn affirmation or declaration, made with a reverent appeal to God for the truth of what is affirmed.
• noun A solemn affirmation, connected with a sacred object, or one regarded as sacred, as the temple, the altar, the blood of Abel, the Bible, the Koran, etc.
• noun (Law) An appeal (in verification of a statement made) to a superior sanction, in such a form as exposes the party making the appeal to an indictment for perjury if the statement be false.
• noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A solemn pledge or promise to a god, king, or another person, to attest to the truth of a statement or contract
• noun the affirmed statement or promise accepted as equivalent to an oath
• noun A light or insulting use of a solemn pledge or promise to a god, king or another person, to attest to the truth of a statement or contract the name of a deity in a profanity, as in swearing oaths
• noun a curse
• noun law An affirmation of the truth of a statement.
• verb archaic To pledge.
• verb Shouting out. (as in 'oathing obsenities')

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a commitment to tell the truth (especially in a court of law); to lie under oath is to become subject to prosecution for perjury
• noun a solemn promise, usually invoking a divine witness, regarding your future acts or behavior
• noun profane or obscene expression usually of surprise or anger