The purpose of this article is to identify some reasons for the appearance of lexical errors in the written English language of undergraduate and graduate students of non-linguistic specialties and ways to prevent and / or correct such errors.Typical errors of students are the use of the direct meaning of a word instead of a figurative one, transfers of a given lexical correspondence to all combinations of a given word, errors in choosing the contextual meaning of a multi-valued word.As a result, students acquire metacognitive skills to classify the information received, organize it into related structures, and analyze the meanings of words Differences between the native language (L1) and the target language (L2) can lead to a fuzzy expression of the author’s thoughts in a language that is not native to him, since very often the words of the source language have a completely different meaning in the target language.