R. S. Ginzburg, S. S. Khidekel, G. Y. Knyazeva, A. A. Sankin a course in modern english

§ 12. Derivational Types of Words

According to their derivational structure words fall into two large classes: simple, non-derived words or simplexes and derivatives or complexes. Complexes are classified according to the type of the underlying derivational pattern into: derived and compound words. Derived words fall into affixational words, which in their turn must be classified into suffixal and prefixal derivatives, and conversions. Each derivational type of words is unequally represented in different parts of speech.
Comparing the role each of these structural type of words plays in the language we can easily perceive that the clue to the correct understanding of their comparative value lies in a careful consideration of 1) the importance of each type in the existing word-stock and 2) their frequency value in actual speech. Of the two factors frequency is by far the most important. According to the available word counts in different parts of speech, we find that derived words numerically constitute the largest class of words in the existing word-stock, derived nouns comprise approximately 67% of the total number and adjectives about 86%, whereas
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compound nouns make about 15% and adjectives only about 4%. Simple words come to 18% in nouns, i.e. a trifle more than the number of compound words; in adjectives simple words come to approximately 12%.¹ But if we now consider the frequency value of these types of words in actual speech, we cannot fail to see that simple words occupy a predominant place in English. According to recent frequency counts, about 60% of the total number of nouns and 62% of the total number of adjectives in current use are simple words. Of the total number of adjectives and nouns, derived words comprise about 38% and 37% respectively while compound words comprise an insignificant 2% in nouns and 0.2% in adjectives.² Thus it is the simple, non-derived words that constitute the foundation and the backbone of the vocabulary and that are of paramount importance in speech. It should also be mentioned that non-derived words are characterised by a high degree of collocability and a complex variety of meanings in contrast with words of other structural types whose semantic structures are much poorer. Simple words also serve as basic parent forms motivating all types of derived and compound words. At the same time it should be pointed out that new words that appear in the vocabulary are mostly words of derived and compound structure.