Generally, it could be considered that the object of word formation as a branch of linguistics is the word, which is also investigated in other sections of linguistic science. The significant difference between word formation and other branches of linguistics is that it does not study all the words of the language, but only derivative words. Derivative words are explored in word-formation not on their own, as separately taken units of the vocabulary of the language, but in relation to the correspondence of the choice of leading in relationship with other derivatives, the same type in their word-formation structure in the way of word formation. Therefore, as linguistic units, studied in word formation, should be considered not only individual derivative words, but also certain categories, combinations of derivatives of words, and other general formal and semantic features. Among the elementary linguistic units that serve as the word formation, there are various word-formation means, more precisely the derivation of stems, connecting sounds and other elements of the linguistic structure, standing out in the derivatives of words. The historical word-formation is composed of such words that were once formed on the basis of previously existing words, without concentration on the structure, character and relationship with other words of the language or another type of development.
The descriptive word formation could solely be words that are perceived by speakers as derivatives, as formed on the basis of other words in the depicted development of the language, as well as such parts of words that in the cognition of speakers are freely distinguished as derivatives when they are associated with other words of the language. According to Kubryakova, «only such correlative pairs are included in the synchronous word-formation system, the existence of which is easily verified by repeatability under the same conditions’’. In this case, the fundamental role is played by the moment of structural-semantic correlation of initial derived language units. In modern linguistics, it is widely accepted that in descriptive word formation only regular productive and active elements of the word-formation system of the language should be scrutinized- word-forming means, word-forming types, models. Another, opposite point of view on the descriptive word formation, according to which, all living word-formation elements operating in the modern language (both regular, productive and active, as well as irregular, unproductive, passive). In general all derived words, which in the minds of modern language users are motivated by other words with the same root. At the same time, one cannot but agree with the opinion of Academic V.V. Vinogradov that when describing the system of modern word-formation, the main emphasis should be placed not on single, irregular, unproductive or word-forming types, but on types are stable, leading a life for a very long time, productive and developing again.
Only such correlative pairs are included in the synchronous word formation system, the existence of which is easily verified by repeatability under the same conditions. In this case, the fundamental role is played by the moment of structuralsemantic correlation of initial derived language units. In modern linguistics, it is widely accepted that in descriptive word formation only regular productive and active elements of the wordformation system of the language should be scrutinized wordforming means, forming types, models. Another, opposite point of view on the descriptive word formation, according to which, all living wordformation elements operating in the modern language. Descriptive word-formation studies derivative words and other word-formation units according to their state at a certain stage of language development, without taking into account their alterations. Historical word formation deals with the study of various word-formation processes correlates with the formation and change of the corresponding word-formation units. According to E. A. Zemskaya, «synchronous word formation studies the relations of coexisting units, diachronic — the processes of transformation of some units into others". Separate questions of historical word formation are considered merely to the extent necessary for a better understanding of other word-formation phenomena of a synchronic nature. The words of the modern language consist of units of a lower level, first of all, morphemes, which are associated with each other in a certain way, and in certain relations to each other, demonstrate a certain structure. The study of the structure of the word, its constituent parts, various relationships between them is one of the main, most fundamental tasks of descriptive word formation. In view of the fact that derivative words are investaged in word-formation, the synchronic word-formation derivativeness between related, cognate words, the delimitation of synchronously derived of words, the definition of relations from non-derivative ones, has also importance. In this regard, in descriptive word formation, first of all, to study specific formal and semantic features of synchronously derived words that differentiate them from non-derivative words, specific methods of distinguishing synchronously derived and non-derivative words. One of the most structural features of synchronously derived words is the way they are word — formed that are from a synchronic point of view. At the same time, the study of word-formation means, or formats, by which of word formation are determined, is of particular importance. Derivative words of a special way of word formation differ in a number of other, less significant formal features. This is the lexico-grammatical peculiarity of generating words, they belong to one or another part of the part of speech, phonetic structure of word-formation morphemes, presence or absence in the composition of derivative words of various, connecting elements and so on. The formal character of derivative words is also included in the word formation.