Б. С. Хаймович, Б. И. Роговская теоретическая грамматика английского языка

Conversion is a way of forming new lexemes from already existing ones by means of changing the paradigm, the lexico-grammatical meaning, the combinability and the function, or only the last three features.
T his definition covers not only cases like the one discussed above (doctor n. doctor v.) but also changes of the type break v. break п., smooth a. smooth v., native a. native п., home n. home adv., down adv. down v., down adv. down п., down adv. down prep., etc. In cases like down adv. down v. the basic lexeme has no paradigm, and the derived lexeme has a developed paradigm. In down adv. down prep both lexemes are without paradigms and are distinguished only by their lexico-grammatical meanings, combinability and functions.
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¹ This is how Donald W. Lee defines it: "Functional change is the process whereby a word conies to be used in a new grammatical function with no salient change of form, i. e. without the addition or subtraction of a derivative syllable or other similar element." (Functional Change in Early English. Diss, Wisconsin, 1948).

§ 58. Some linguists do not regard the substantivization of adjectives (native a. native n.) and the adverbialization of nouns (home n. home adv.) as types of conversion on account of their slow progress, as distinct from the instanta­neous nature of changes like doctor n. doctor v. The so-called 'partial substantivization of adjectives' (see § 109) can be used as an argument in favour of such views. The adjective native was first partially substantivized, then fully. But we may also have partial substantivization in cases like to smoke a smoke (in to have a smoke) where the change was instantaneous.

A nyhow, in cases of full substantivization the results do not differ from those of other kinds of conversion. We might call changes of the type doctor n. doctor v. the verbaliza­tion of nouns, break v. break n. — the substantivization of verbs, better a. better n. — the verbalization of adjectives, etc.

§ 59. Summing up, we may say that lexeme-building is closely connected with the division of lexemes into parts of speech, the characteristic features of the latter discharging the functions of lexeme-building means.

When no reference to the history of derivation is made, and no emphasis is laid on the fact that doctor n. is the basic lexeme and doctor v. has been derived by conversion, we can simply say that doctor n. and doctor v. are related by conversion.
One of the characteristic features of English is the abun­dance of lexemes related by conversion.

§ 60. A part of speech can usually be subdivided into smaller lexico-grammatical classes, or subclasses. This sub­division can be based on the same principles which serve to distinguish parts of speech.

Let us by way of illustration compare the nouns boy, friend, on the one hand, and boyhood, friendship, on the other. All the lexemes represented by these words have the features of English noun lexemes. Yet, these nouns are not homoge­neous.
They are united by the lexico-grammatical meaning of 'substance', but boy and friend denote 'countable substances', whereas boyhood and friendship stand for 'uncountable sub­stances'.
Boy and friend have simple stems, while boyhood and friendship have been derived by means of affixa­tion.
The lexemes of boy and friend have four-member paradigms, whereas the lexemes of boyhood and friendship are one-member ones.
The combinability of these words, though essentially alike, is not without certain distinctions. Unlike boy and friend, for instance, boyhood and friendship do not form combinations with numerals.
Thus, within the same lexico-grammatical class of nouns these lexemes belong to different subclasses.

§ 61. So far no systematic analysis of the subclasses of parts of speech has been carried out. Before this is done, it seems feasible to subdivide the lexemes of a part of speech with regard to some leading feature. From the grammatical point of view it is most essential to classify lexemes with regard to the grammatical categories of the part of speech they belong to.

With regard to the category of number, for instance, noun lexemes can be divided into those which possess number oppo­semes (boy — boys, book — books) and those having no number opposemes (snow, darkness, trousers). These two subclasses are roughly covered by the terms countables and uncountables and we shall call them so, though the un­countability of trousers, tongs or nuptials is rather doubt­ful.
With regard to the category of case nouns are subdivided into those having case opposemes (man — man's) and those without such opposemes (table, food). The first subclass mostly contains nouns denoting living beings and the second — lifeless things. But instances like a night's rest, a mile's distance, etc. show the need for more adequate terms, possibly, declinables and indeclinables.
Similarly, adjective lexemes can be divided into those possessing opposemes of the degrees of comparison (long — longer — longest, beautiful — more beautiful — most beauti­ful) and those having no such opposemes (wooden, deaf). These two subclasses are to some extent covered by the terms qualitative and relative. But adjectives like deaf, blind, etc. show the inaccuracy of these terms from the grammatical point of view. It would be more in keeping with grammar to call these classes comparables and non-comparables respectively.
English verbs can also be divided into subclasses, for instance, with regard to the category of voice. Some verb lexemes contain voice opposemes (takes — is taken, wants — is wanted), others do not (sit, resemble). The two subclasses are more or less covered by the terms objective and subjec­tive ¹, though these terms refer to the combinability of the corresponding verbs, not to their paradigms.
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1}See § 204.

§ 62. Different lexemes usually belong to different sub­classes, but often the dividing line passes within the lexeme. One of the meanings of the noun beauty is "all those qualities that give pleasure to the mind or to the eye or ear", e. g. В e а и t у is only skin deep. In this meaning the word beauty has neither a case nor a number opposite and belongs to the subclass of uncountable indeclinable nouns, like hatred, milk, etc.

When beauty means "an example of what is beautiful" (Her smile was one of her chief beauties) it has a number opposite and belongs to the subclass of countable indeclinable nouns, like book, day, etc. When meaning "beautiful woman" (She is a real beauty) beauty has both a case and a number opposites and belongs to the subclass of countable declinable nouns, like woman, student, etc. Strictly speaking, we might regard beauty in the first meaning as a separate lexeme con­sisting of one word. The second meaning might be looked upon as uniting two words (beauty, beauties) in another lexeme, the third meaning, as uniting four words (beauty, beauties, beauty's, beauties') in a different lexeme. But the connection between those meanings is so close and obvious that beauty_l, beauty₂, beauty₃ can hardly be considered homonyms. We shall rather regard them as variants of one lexeme.

§ 63. The relations between these variants remind us of conversion:

1. The variants belong to different lexico-grammatical subclasses.
2. They have different paradigms.
3. There is some difference in their combinability (e. g. unlike beauty₂ and beauty₃, beauty₁ cannot be associated with the indefinite article or numerals).
We shall assume then that beauty₁, beauty₂ and beauty₃. are related by internal conversion, i. e. conversion within the same part of speech.
Variants of lexemes related by internal conversion are not uncommon in other parts of speech either. The verb lexeme represented by the word runs (see § 19) consists of at least two variants. The first three meanings unite one variant be­longing to the subclass of subjective verbs. The second variant, united by the last two meanings, belongs to the subclass of objective, more exactly, transitive verbs ¹. These variants, as well as the corresponding subclasses, differ from each other in their paradigms and combinability. Unlike runs₁, runs₂ has
a voice opposite — is run and is followed by a noun in the common case or a pronoun in the objective case ².
Sometimes variants of a lexeme have different forms of the same opposemes. Cf. brother — brothers and brother — brethren.
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1}See § 198.
²See § 200.