Throughout their history, Jews have repeatedly lived in environments of foreign culture and language. In a foreign area they were a minority, which is why they quickly succumbed to the linguistic pressure of the environment. In addition to their native language, they began to use the language of the natives. They became bilingual. The contact of these two languages caused the occurrence of the process of interference (overlapping of languages), which consists in departing from the norm of one of the languages in the speech of a bilingual person. As a result of interference, a number of phonetic, morphological and lexical changes occur in the colloquial use of these languages. The next phase of language contact was the change of language. As a result of the change of language, the features of one of the languages were replaced by the features of the other, usually the language of the environment. As a result, the last phase of language contact was the process of forming a new hybrid language e.g. Yiddish or Judeoespañol.