Weasel words are words used by marketing people to limit the scope of any claim. They're used to allow the person making the statement to "weasel out" of what he's saying, but still say it.
For instance, when Kodak's PR about Ektar 100 says that it has the "finest, smoothest grain of any color negative film available today," the weasel words "color negative" just allowed Kodak to ignore the black-and-white and slide films that have finer grain, and by adding "available today," chooses to ignore that discontinued Ektar 25 had finer grain.
If you understand weasel words, Kodak is saying that other kinds of film have better grain today, and that some discontinued older films were better, too.
Otherwise Kodak would simply say that Ektar 100 has "the finest, smoothest grain of any film," but they can't because it's not true.
When I say the Mamiya 7 is the world's best camera, I mean it.
When I say the Nikon D700 is the world's best digital camera, notice how the word "digital" just limited the field of cameras to which I'm comparing it. The Mamiya 7 is a better camera, but it's not digital. When I say "world's best digital camera," I just removed all other cameras from consideration.
Nikon's 13mm f/5.6 is the world's widest non-distorting professional SLR lens. There are three weasel words in that sentence, and the only reason I use them is so that I can pitch the 13mm lens as being something special.
The world's widest lenses are Nikon's 6mm 220º fisheyes. Other ordinary fisheyes see 180º. By using the phrase "non-distorting," I just took all the fisheyes out of competition.
By using the word "professional," I just threw out the Sigma 12-24mm zoom, which is wider, but not professional grade. (Some might say I can ignore the Sigma as a lens, because it's not a lens, it's a zoom lens.)
By using the acronym "SLR," I eliminated the Cosina 12mm lens from the pack. That Cosina (branded as Voigtländer) is a rangefinder, not SLR, lens.
Anytime you see a claim with added words, those words are telling you that there is some other product which is superior, and that the person making the claim is using weasel words to exclude them from consideration.
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