In rhetoric, a weasel word, or anonymous authority, is a word or phrase aimed at creating an impression that something specific and meaningful has been said, when in fact only a vague, ambiguous, or irrelevant claim has been communicated. The terms may be considered informal. Examples include the phrases "some people say", "it is thought", and "researchers believe". Using weasel words may allow one to later deny any specific meaning if the statement is challenged, because the statement was never specific in the first place. Weasel words can be a form of tergiversation and may be used in conspiracy theories, advertising, popular science, opinion pieces and political statements to mislead or disguise a biased view or unsubstantiated claim.