Introduction
Tangsir novel is an outstanding naturalist work in Persian fiction. The naturalistic work is written based on descriptions and adjectives and predicates have many functions. In this essay, the descriptive function of adjective and predicate in the novel Tangsir, by Sadegh Chubak, has been investigated. What kind of metagrammatical function can adjectives and predicates have in the formation of the writer's literary doctrine, the treatment of characters in the story, and the creation of atmosphere. Examining the aesthetic function and the semantic function of the descriptive role of predicate and adjective and comparing these two grammatical roles in the formation of the main components of the naturalism doctrine can lead to important results in literary criticism, which is a great strategy for the authors of this doctrine in paying attention to their main components according to the function Grammar of vocabulary. Therefore, the present research answers the question that what is the meta-grammatical function of predicate and adjective in Tangsir novel and the literary doctrine of naturalism?
 
Research Methodology
This research is descriptive-analytical. Based on this, this research was prepared by extracting and analyzing the adjectives and predicates in the text of the novel "Tangsir".
 
Discuss
Tangsir is the story of suffocation. the story of the suffocation of the proletariat; Accordingly, documentary sentences that confirm this content have been used a lot. In this section, the adjective has a more prominent function; Because in this section, the frequency of words is very important. The adjective gives color to the whole text and the author has used it more in this section. The difference is small, for example, the color black is repeated 19 times as a predicate; But as an adjective 21 times, in general, it can be said that the adjective was more useful for the author in this section. In addition to suffocation, just as the author has taken the style and atmosphere of the story to darkness and the bitter human truth by using adjectives indicating the blackness of the atmosphere and the life of the lower class, he also uses the preposition in the same direction, which has a complementary role to the adjective. The word dark as a predicate has a high frequency, it is repeated 16 times as a predicate in the story, and the word black 19 times, while the word light as a predicate in Tangsir's novel, such as words like light, is used a total of 10 times, and the color white is used 10 times.
 
Conclusion
In describing the characters of his story, the author has used descriptive tools such as prepositions and adjectives, among which prepositions are more functional. The number of predicates used for characterizing has been more than the number of adjectives; Because it is more difficult for the author to create descriptive sentences than to use independent documentary sentences to describe the characters of his story. In the field of literary function, the adjective has more functions; Because it has a literary structure and makes the text of the story more imaginative. The literature that the author has given to the text with the adjective has a major difference with the literary function of the predicate. The highest function of adjectives in this section can be seen in compound adjectives and compound derivatives, which have both norm-avoidance and literary functions, such as creating metaphors. 23 compound adjectives and 48 compound derivative adjectives are used in Tangsir's novel. The structure of the adjective has an effect on its literary function, which the author has given to the text by using and creating compound derivative adjectives; But the number of predicates that created a literary function in the text was very limited and they did not add literaryness to the text to the extent of adjectives. In the comparison of the use of colors in order to create space and the literary doctrine, the colors used as attributes have more variety, and therefore they can help the author more in creating space; But the two most frequent colors, white and black, were almost equal, and the frequency of black is used more frequently than white, either as a predicate or as an adjective, which creates a dark background in the story. A small amount of black color can be seen in the text, which can be concluded that the text has given a darker atmosphere to the story. But because the variety of colors in the predicate is less, creating space with colors is mostly created with adjectives.