This paper investigates the possible anti-Semitic nuances present in some examples of Polish language. The article analyses the different meanings of the word 'zyd' ('Jewish') in set phrases which originally were the result of anti-Semitic attitudes, but now have become clichés. Although this xenophobic nuance is not perceivable by the average speaker, it has a very different effect on children. Indeed, children get a distorted semantic definition of the word 'zyd' from those set phrases. Therefore, they attribute to this word the various meanings which appear in set phrases: mean, rude, noisy, conceited, negligent, dirty, etc. This is perhaps the reason why anti-Semitic prejudices appear especially among the less cultivated speakers: peasants and unskilled workers. This phenomenon, quite dangerous since it is widespread, could disappear from the language when this kind of expressions falls into disuse.