The quantity of terms in developed languages sometimes exceeds the quantity of common words and reaches now several millions of lexical units. This quantity permanently grows.

Terminological units enter a language in different ways. The first way is common lexical units of the native language acquire the status of terms.

This way of coining terms is not always positive: some metonymic transferrings may take place when a word acquires new (already terminological) shadows of meaning (for example, such terms as "shoulder", "chairman", "circuit", etc.).

To differentiate similar lexical units, terms frequently change their spelling form or pronunciation, their declination, their stress.

More frequently used is the way of formation of terminological units by borrowing words and morphemes from other languages.

In different epochs terms used to be borrowed from different languages. These source languages were predetermined by different historical conditions.

Thus, musical and commercial terminology of the leading European languages is mostly of the Italian origin (legato, adagio, andante, bank, àgio, aviso, loro, al pari etc.); theaterl and post terms originate from French (interval, orchestra, courier, lessez-passer). The majority of sports terms were borrowed from English (football, champion, ring). The navy terminology in Russian, English and some other languages consists of Dutch lexical elements (deck, rijd etc). Technical, craft and military terminologies in many Slavic languages have numerous borrowings from German (Ukrainian verstat, kronštejn, erker, plac, brustver, fel´dfebel´, štandart).

A special type of loan words constitutes the words and word-formation models of the Greek and Latin origin.

Such terms were formed at different stages of the development of a language, and in different terminological spheres. The church terminology in the languages of the Roman Catholic area originate basically from the Latin elements; languages of the Byzantine Orthodox area use borrowings of the Greek origin.

It is necessary to specify that entirely new terms are not invented as a rule. For the whole history of the development of science and technologies, it is possible to recollect only several cases of such a way of coining.

A special case of the formation of terminological units consists in borrowing a term from one branch of science into another. A term borrowed from another branch often acquires new meanings (for example, morphology in linguistics and biology; speech in linguistics, rhetoric, psychology, physiology and medicine etc.).

Term, as well as all others language universals, has many variants of definition.

On account of its complexity, there are many diverse attempts of definition of the concept. Here we place only two definitions of the concept, which displays and synthesizes, in our opinion, different approaches to the concept of a term, moreover they may supplement each other.

B.N.Golovin writes that term is a separate word or a word-combination formed on the basis of a noun, which denotes a professional concept and is intended for satisfaction of specific needs in the process of communication within a certain branch (of science, technology, industry, social life etc.) [Golovin 1980, p. 276].

This definition is rather successful and capacious, though some moments can cause objections. Doubtful is particularly the fact that all terms may be formed on the basis of nouns only. Sometimes verbs (in particular in the chess terminology), adverbs (in particular in the musical terminology), adjectives can also be such a base [Danilenko 1972, p. 9].

The expression "specific needs in the process of communication" is not absolutely clear here. The functions of the term in the paradigmatic aspect are also poorly displayed. The differences between terms and common words are not specified too.

On the basis of various definitions, I.S.Kvitko offers an interesting "generalizing" definition: "term is a word or a verbal complex, which has some correlation with the concepts of a certain branch (of science or technologies); these concepts have system relations with other words and verbal complexes and form a certain closed system together with them. This system is characterized by a high degree of self-descriptiveness, unambiguity, accuracy and expressive neutrality" [Kvitko 1976, p. 21].

Rather short and precise is the definition of the concept given by the Committee of the Scientific and Technical Terminology at the Academy of Sciences of the USSR (KNTT): "a term (a word or a word-combination) is a unity of a sound sign and the correlated corresponding concept, which is connected with other concepts of this branch" [Klimoveckij 1967, p. 34].

Speaking about terminology, linguists as a rule, distinguish:

1. the science about terms (in this respect the term "terminological science" becomes the most popular;
2. professional vocabularies in the structure of all the words in a certain language (if we speak, for example, about the terminology of the Ukrainian language, or the German terminology, etc.);
3. a special vocabulary, which serves to satisfy the needs of a certain branch of science or technologies (for example, the terminology of computer science, the linguistic a terminology, etc.).

The polysemy of such a kind may be caused by the reason that each terminological unit is given a certain point in the coordinates both in language as a whole, and in sublanguages in particular.

Term is an integral element of the system, if this system is understood as a set of elements of the whole, which have a strong interconnection between each other. A set of interconnections within such an integrity, defines its structure.

Moreover some linguists also distinguish scientific and technical terminological systems. So, J.Vignet and A.Martin emphasize, that this distinction is caused by the existence sciences and technologies themselves, as technologies have arisen as a result of numerous of tests and mistakes, which were frequently carried out at random. That was a result of empirical searches of handicraftsmen; the science developed in its own way and, being released from primary mystical and religious representations, only at the beginning of the 19^th century due to the new achievements, it could give a new pulse to dissemination of technical knowledge. Therefore it is impossible to consider that science and technologies belong to one and the same sphere of thinking and can be expressed in a language with identical linguistic devises… In each case language uses different concepts and different own syntactic devises [Vin´e, Martèn 1981, p. 11].

At the same time it is necessary to recognize that during the epoch of rapid development of science and technologies these two spheres of human activity develop in parallel, complying and enriching each other.

Today it is already more logical to assert about the existence of language of science, within which the language of technologies is located. The modern language of science and technologies puts forward some requirements to terms. The most important of them are the following:

1. Terms should meet the rules and norms of the corresponding language.
2. Terms should be regular.
3. Terms should possess an inherent property of definitiveness. That means that each term should be precisely associated with the corresponding definition and the corresponding concept.
4. Terms should be relatively independent of a context.
5. Terms should be exact, though in some sublanguages numerous terms with false associations (according to D.S.Lotte) may take place.
6. Terms should be concise; though this requirement quite often contradicts the requirement of accuracy, that is completeness of the term.
7. Terms should be monosemantic (here it is necessary to make one important specification: such unambiguity should be achieved within one terminological system of a particular sublanguage; on the level of several sublanguages the polysemy of terms is quite admittable).
8. Terminology should be free from synymy, which prevents mutual understanding.
9. Terms should be expressively neutral.
10. Terms should be euphonic; therefore terms, which originate from dialecticisms, jargonisms and barbarisms are not desired.

On the other hand, terms are not isolated, independent units of the general language, with properties inherent to them only. They, to the contrary, constitute a full-value part of the general structure of language, where properties of words are apparent in a more determined way, in accordance with the requirements of professional communications and mutual understanding.

Thus, it is possible to speak about the prevailing character of term in comparison with a common word instead of speaking about the full absence of this or that feature within different spheres of language. It is possible to assert about some desirable properties of terminological units, but it is impossible to consider them defective or unnecessary only on account of the fact that this unit has no such properties, though this term is applied by users for a long time.

The word-formation architectonics of terminological units possesses actually the same principles, as the one of common units. One can specify the following word-formation types of terms.

1. Terms that are root words:

1. root words from the native language;
2. borrowed elements.

2. Derivative elements:

1. terms coined with the help of suffixation;
2. terms coined with the help of prefixatin.

3. Compound terms.
4. Terminological phrases. It is necessary to note here that many linguists do not recognize the presence of terminological phrases in a language; they call them "conceptual associations". Such an opinion should be checked by the general requirements to the term mentioned above: if a term meets all these requirements, there are no reasons for refusal to consider this or that phrase a term, irrespective of its lexical length.
5. Terminological abbreviations.
6. Alphabetic symbols (like gamma-radiation).
7. Special symbols (signs)—for example in mathematics, chemistry, astronomy and other sciences.
8. Nomenclatures.

The problem of differentiation between professional vocabularies and terminologies remains rather complicated. Some linguists identify those two concepts, the others differentiate them specifying strict criteria to define, whether this or that lexical unit is a term or a professional word (phrase). Linguists from the third group admit the presence of some common features among them. The first point of view is supported by M.M.Šanskij. He said that professionalisms denote special concepts for tools, processes or products; therefore they are terms too [Šanskij 1972, s. 124].

This approach can be understood when one aspect is taken into consideration: the common features for terminology and professional vocabulary are specialized meanings and specific lexico-semantic systems created on their basis, as well as a limited number of people that use this vocabulary.

It is considered logical that the development of mechanization of actually all the production processes as well as the introduction of new technologies, reduced the sphere of application of professional sublanguages.

However the adherents of this point of view are too categorical in the judgment that professional jargonisms differ from terms too greatly, and that terminological units are clearer and more precise.

Statements about the territorial limitation of professional vocabularies are also insufficiently argumented. The most consistent here is the concept about the nomination of the most ancient special concepts, which belong to the labour and industrial activity, as well as the existence of their connection with corresponding terminologies. Thus, the problem of greater archaism of professional vocabulary loses its relevance. S.D.Šelov fairly marks that the special vocabulary of labour activity frequently outstrips its specialization and professionalization. In this context, terms as the special, thematically limited designations seem to be not newer, but on the contrary, older than professional lexemes [Šelov 1984, p. 80].

Expedient is the delimitation of professional jargonisms and terms, which are bound together with the concepts of special sublanguages. Bordering on each other, terms nevertheless have a better-ordered and more normalized character, while professional jargonisms are semi-official lexical units used by narrow circles of experts and mainly in the oral communication. Despite of these essential differences, there is permanent interchange between these two spheres of vocabulary. Professionalisms may also exist as synonyms of corresponding terms.

Terms are not special words but only words in special functions. The special function, in which a word is used, is a function of nomination… Meanwhile, branch term is an integral part of a concept [Vinokur 1939, p. 5-6].

V.V.Vinogradov specifies another important function of terms, i.e. the definitive function [Vinogradov 1947, p. 12-13].

This function of terms is not inherent to another group of lexical units used in professional sublanguages, which possess the function of nomination too. It is a question of nomenclature formations, which are often included into terminological dictionaries and falsely considered by some linguists as terms (for example, such nomens as "Boeing-747", "Mercedes-Benz 250", "HP LaserJet 1100", "Microsoft Office 2000" etc.).

Nomen is actually a "label" of a subject, which is conventionally "attached" by the representatives of this or that corresponding branch; it need not possess any definition or any lexical meaning.

At the same time, the solution of the problem of normalization of nomenclature formations does not belong as a whole to the competence of linguistics. Norms in the sphere of original signs, symbols and nomenclatures do not require any coordination with language norms (sometimes even spelling rules); they are established not by linguists but by experts of a corresponding branch.