Weasel words is an informal term for words and phrases that, while communicating a vague or ambiguous claim, create an impression that something specific and meaningful has been said. Weasel words manage to vaguely imply meaning far beyond the claim actually made. For example, advertisements use weasel phrases such as "up to 50% off": this is misleading because readers are invited to imagine many reduced items and many of them reduced by as much as the proclaimed 50%, but the words taken literally allow for much less. Some weasel words may also have the effect of softening the force of a potentially loaded or otherwise controversial statement through some form of understatement, for example using detensifiers such as "somewhat" or "in most respects".
The expression weasel word derives from the egg-eating habits of weasels. An egg that a weasel has sucked will look intact to the casual observer, while actually being empty. Thus, words or claims that turn out to be empty upon analysis are known as "weasel words". The expression first appeared in Stewart Chaplin's short story Stained Glass Political Platform (published in 1900 in The Century Magazine), in which they were referred to as "words that suck the life out of the words next to them, just as a weasel sucks the egg and leaves the shell." Theodore Roosevelt attributed the term to Dave Sewall, claiming that Sewall used the term in a private conversation in 1879.
In the political sphere, this type of language is used to "spin" or alter the public's perception of an issue. In 1916, Theodore Roosevelt argued that "one of our defects as a nation is a tendency to use ...'weasel words'; when one 'weasel word' is used ... after another there is nothing left."
Other forms of weasel words include:
The vagueness of a statement may disguise the validity or the aim of that statement. Generalizing by means of quantifiers, such as many or better, and the passive voice ("it has been decided") conceal the full picture.
Non sequitur statements are often used in advertising to make it appear that the statement is a sales point. Some generalizations are considered unacceptable in writing. This category embraces what is termed a "semantic cop-out", represented by the term allegedly. This phrase, which became something of a catch phrase on the weekly satirical BBC television series Have I Got News For You, implies an absence of ownership of opinion, which casts a limited doubt on the opinion being articulated.
Extrapolating through the use of grammatical devices such as qualifiers and the subjunctive can be used to introduce facts that are beyond the proof of the cited work. This is a legitimate function of language, which resembles weaseling. When it is impractical to enumerate and cite many individual works, then the use of these grammatical devices conforms to the standards established by tradition. For example: "For scientists as for so many others, evolution served as an example of a fundamental challenge to long-held convictions".
Also rhetorically valid is the use of the neuter pronoun it and the adverb there as impersonal dummy subjects, as when an author intends to distance himself/herself from the work, or to separate one part of the text from another:
The personal pronoun one, as a subject or an object in formal speech, that refers either to oneself or as a generalization to anyone in a similar situation, may also be used justifiably to distance a speaker from a subject.
The passive voice and middle voice can both be used in English to weasel away from blame. A passive construction occurs when the object of an action is made the focus of the sentence (by moving it to the front). In some cases, the agent (the subject in active voice, usually indicated by "by" in the passive voice) is missing altogether, as the sentence "mistakes were made by the politicians," for example, has been curtailed deliberately to "mistakes were made."
In the example: "Mistakes were made," it is clear that the names of the persons who made mistakes is being withheld and the intention of weaseling is obvious.
In the "over 120 different contaminants..." sentence, a more precise number of "contaminants" might have avoided the impression of weaseling, even though we might never know who the "dumpers" were.
A related issue is the stylistic qualms held by linguists and teachers who discourage the passive voice being used too frequently. However, in the sentence
the usage of the passive voice is not necessarily connected with weaseling. The phrase, "100 votes are required to pass the bill", is probably a statement of fact, that it is exactly 100 votes that are needed for the passing of the bill, and it might be impossible to predict where these votes are to come from. For a statement to be a weasel expression, it needs other indications of disingenuousness than the mere fact that it is expressed in the passive voice.
Examples of weasel words using the middle voice are:
Not all sentences using the middle voice are necessarily weasel words. The above sentence: "It stands to reason that most people will be better off after the changes", is clearly an instance of redundancy rather than weaseling. There is no need for "it stands to reason..." All that is needed is: "More people will be better off after the changes". What is relevant is what has been said before or is going to be said afterwards in the context of the discussion where the sentence occurs.
Style is another point more important in the discernment of the use of middle or passive voice. The above sentence: "There are great fears..." would have been better in the passive voice: "It is feared that most people will be worse off after the changes". The passive voice is the more logical choice here for the reason that this sentence would not stand on its own, but would occur in the course of a discussion. If the reasoning behind the sentence is so obvious within the discussion that it does not need substantiating by citing thousands of sources then the passive is perfectly alright.
Weasel words may be used to detract from an uncomfortable fact, such as the act of firing staff. By replacing "firing staff" with "headcount reduction", one may soften meaning. Jargon of this kind is used to describe things euphemistically.
In certain kinds of advertisements, words are missing or withheld deliberately to influence the buyer. Words such as more or better are misleading due to the absence of a comparison:
In Report on Unidentified Flying Objects (1956), U.S. Air Force Captain Edward J. Ruppelt described astronomer Dr. J. Allen Hynek's report on the death of Air Force Pilot Thomas Mantell in pursuit of a UFO as "a masterpiece in the art of 'weasel wording'."
Carl Wrighter discussed weasel words in his book I Can Sell You Anything (1972).
Australian author Don Watson collected two volumes (Death Sentence and Watson's Dictionary of Weasel Words) documenting the increasing use of weasel words in government and corporate language. He maintains a website encouraging people to identify and nominate examples of weasel words.