И. В. Арнольд лексикология современного английского языка Издание

§ 8.6 CONVERSION IN DIFFERENT PARTS OF SPEECH
In this paragraph we present the types of conversion according to parts of speech and secondary word classes involved. By secondary word classes we mean lexico-grammatical classes, that is subsets within parts of speech that differ in meaning and functions, as, for instance, transitive and intransitive verbs, countable and uncountable nouns, gradable and non-gradable adjectives, and so on.
We know already that the most frequent types of conversion are those from noun to verb, from verb to noun and from adjective to noun and to verb. The first type seems especially important, conversion being the main process of verb-formation at present.
Less frequent but also quite possible is conversion from form words to nouns. E. g. He liked to know the ins and outs. I shan’t go into the whys and wherefores. He was familiar with ups and downs of life. Use is even made of affixes. Thus, ism is a separate word nowadays meaning ‘a set of ideas or principles’, e. g. Freudism, existentialism and all the other isms.
In all the above examples the change of paradigm is present and helpful for classifying the newly coined words as cases of conversion. But it is not absolutely necessary, because conversion is not limited to such parts of speech which possess a paradigm. That, for example, may be converted into an adverb in informal speech: I was that hungry I could have eaten a horse.
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R. Quirk and his colleagues extend the notion of conversion to re-classification of secondary word classes within one part of speech, a phenomenon also called transposition. Thus, mass nouns and abstract nouns are converted into countable nouns with the meanings ‘a unit of N’, ‘a kind of N’, ‘an instance of N’. E. g. two coffees, different oils (esp. in technical literature), peaceful initiatives.
The next commonest change is changing of intransitive verbs into transitive: to run a horse in a race, to march the prisoners, to dive a plane. Other secondary verb-classes can be changed likewise. Non-gradable adjectives become gradable with a certain change of meaning: He is more English than the English.
We share a more traditional approach and treat transposition within one part of speech as resulting in lexico-semantic variation of one and the same word, not as coining a new one (see § 3.4).