Teaching English is aimed at developing communicative competence, which consists of linguistic, speech, socio-cultural, compensatory and educational-cognitive competences. Communicative competence, in turn, is based on such competences as lexical, speech, socio-cultural, compensatory, discursive and subject. Let us consider the development of lexical competence, which is the student’s ability to determine the meaning of a word in context, the ability to use it in oral and written form. At the same time, the basis of lexical competence is the lexical skill, which consists of knowledge about the word, its use, as well as its forms and meanings. Lexical skill is formed, in turn, due to the establishment of strong paradigmatic connections of words, including, in addition to word forms, synonyms and antonyms, also words close in context. It is important that paradigmatic connections are formed only with the maturation and change in the child’s thinking, complementing the syntagmatic connections.

Lexical competence is formed within the framework of professionally oriented teaching of the English language, which occurs when the formation of paradigmatic connections becomes possible. These connections determine such important characteristics as the strength of memorization and the extraction of the desired word from long-term memory, contributing to the formation of an active lexical minimum, which is the lexical material that students must use to express thoughts in oral and written form, as well as understand people’s thoughts when communicating.

The effectiveness of working on an active lexical minimum directly depends on a properly organized learning process, so the teacher’s task is to choose such techniques and methods of teaching that can most effectively familiarize students with new lexical units.

One of the effective methods of developing lexical competence in professionally oriented teaching of English is working with a dictionary.

Working with a dictionary has its own characteristics, which determine the strengths and weaknesses of this method in the formation of paradigmatic connections necessary for expanding the active lexical minimum.

Working with a dictionary in English lessons is aimed at enriching the vocabulary of students. It provides the richness of the vocabulary in English as one of the signs of their general development. Therefore, it is very important to teach students to use dictionaries to master the English language. Working with a dictionary develops in students the need for independent and creative search for words necessary for speech activity, and significantly expands information about the lexical richness of the studied English language. Also, this is the most individualized and independent type of educational activity of students, the purpose of this work is the systematic replenishment of the vocabulary of students.

A dictionary is a collection of words (usually in alphabetical order) with explanations, interpretations or with the translation of the meanings of words from one language to another.

The role of dictionaries in the modern world is great. The general function of all dictionaries is to record, systematize, accumulate and store knowledge. It is very important to be able to work with a dictionary, especially when it comes to reading and translating texts. It is also important to develop the ability to search for the necessary lexical unit in the dictionary quickly enough [1].

Most English language learners do not perceive a dictionary as an effective learning tool. They consider a dictionary to be a repository of word meanings, and not a means of improving language proficiency. At the same time, it is obvious that the formation of the necessary level of educational autonomy is impossible without developed skills in using dictionaries.

The task of every English teacher is to develop in students the need to constantly refer to dictionaries, both in class and when completing assignments independently. Meanwhile, in practice, dictionaries have not yet become an urgent necessity as a mandatory educational material. Work with a dictionary should be aimed at systematizing the vocabulary being learned and actively using it in oral and written speech. Also, when working with a dictionary, the types of dictionaries play an important role.

There are the following types of dictionaries based on the functional-semantic principle:

1. Dictionary of compatibility of common vocabulary (3-5 thousand most frequent words), showing the use of words in typical contexts;
2. Educational thematic dictionary (general – within the lexical and phraseological stock provided by the program and special, for example, technical terms);
3. Linguistic and cultural dictionary, which provides information about the background knowledge of the native speaker of a given language, i.e., describes the realities, associations, etiquette, gestures, customs, traditions, etc.;
4. Dictionary of difficulties of a given language (from the point of view of students with a native language), the purpose of which is to prevent the spread of errors and neutralize the interference of the native language;
5. Word-formation dictionary, describing the system of word-formation means;
6. Frequency dictionary, frequency lists of words and phrases (lists of free phrases, phraseological units, synonyms, antonyms, etc.) [2].

When working with professional vocabulary, words should not be presented in isolation from context, since only in a coherent text do they acquire their specific meaning [3].

Today, modern lexicographers have compiled a list of skills necessary for effective work with any of the currently existing dictionaries:

1. Selecting a lexical unit that requires help in the dictionary.
2. Searching a lexical unit in the dictionary:

• searching for lexical units alphabetically;
• searching for the correct title word;
• searching for the correct title word for polysyllabic lexical units;
• choosing the correct title word among homonyms;
• choosing the correct meaning of the sought lexical unit.

3. Searching information in a dictionary entry:

• searching for information about the spelling of a word;
• searching for information about the pronunciation of a word;
• searching for information about the use of a word;
• searching for information about the meaning of a word;
• searching for grammatical information;
• searching for information about the etymology of a word.

4. Selecting a suitable dictionary for reference in accordance with the type of lexical unit and the information sought.

The art of working with different types of dictionaries can be useful not only in the process of mastering the English language, but also for solving communicative, academic or professional tasks of varying complexity. It is also obvious that these skills are complex and by no means simple; they must be consistently and purposefully developed in English classes [4].

The guiding role of the teacher in this matter is difficult to overestimate. The teacher should offer tasks related to working with a dictionary if he wants to successfully develop lexical competence in students. The proposed tasks do not exhaust all possible situations of using dictionaries in class and in the process of independent work on the language. Tasks and exercises for dictionaries can be very diverse, but it is necessary to wisely dose these tasks and remember that the ability to use a dictionary correctly is a complex, multi-component skill and it must be developed in stages and consistently.

Thus, it is possible to highlight a number of important theses related to students’ work with a dictionary:

1. Working with a dictionary is a highly effective method of developing lexical competence in professionally-oriented teaching of the English language;
2. The creative and independent nature of working with a dictionary determines the special value of this method precisely within the framework of professionally-oriented teaching;
3. Competent use of a dictionary is a skill, the development of which requires special attention, despite the apparent simplicity of this method;
4. It is necessary to develop in students a respectful and serious attitude towards working with a dictionary as an effective method of developing lexical competence;
5. Working with a dictionary should be accompanied by the use of English in professional activities, and in case of its absence, it should be compensated for by creating educational and game situations using other methods and techniques of teaching [5].

The ability to effectively use a dictionary is an important skill in developing students’ lexical competence, as well as an indicator of readiness for self-development, linguistic maturity and a guarantee of linguistic literacy.