This article deals with the well-known Russian expression staraya perechnitsa (‘old shrewʼ) in scientifi c and false etymology. There are some arguments for an original stress in the word perechnitsa on the second syllable and the stress movement to the fi rst syllable under infl uence of folk (false) etymology due to a semantic link between the words perec (‘pepperʼ) and perechnitsa (‘old shrewʼ). The word perechnitsa in the dictionary of V. Dahl, is referred to the verb perechitʼ (‘to argue back’) and roots to the Proto-Slavic root * -perk-> russian -perek-. In many Slavic languages there are derivatives of nouns with this root, going back to the Proto-Slavic form *perčьnica, as well as to the masculine version *perčьnica with a generalized seme meaning of ‘some obstacleʼ. In some Slavic languages (Bulgarian, Slovak, Polish and others) the same words with fi gurative meaning. The semantics development of these words was as follows: ‘some obstacleʼ > ‘a person, that is considered to be an obstacleʼ > ‘an naughty, unmanageable man’. There are some proofs of false (folk) etymology of the expression ‘staraya perechnitsa’, that are analyzed in the article, found on the web forums, that could be considered as the evidence of a link between the words staraya perechnitsa ‘old shrewʼ and perec ‘pepperʼ, and perechen’ ‘listʼ in the public consciousness. Comparison with the words perechnik, -nitsa from the V. Dahl’s dictionary and the corresponding words in other Slavic languages also leads to the conclusion that the semantics of the word perechnitsa was modifi ed, and in the modern phraseological combination ‘staraya (chertova) perechnitsa’ does not transmit behavioral (‘disobedienceʼ), but essential (‘maliceʼ) assessment.