The quality or state of being suspicious, questionable, or smelling like fish.
From 'fishy' + '-ness' (suffix indicating a state or quality, from Old English), a standard English word formation for abstracting adjectives into nouns.
The 'fishiness' of a situation has become a standard phrase in English crime and detective fiction—characters detect something by sensing its 'fishiness,' a perfect example of how smell metaphors have become abstract indicators of deception in how we think about trust.
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