We can make a further distinction within the set of bound morphemes in English. One type of bound morphemes consists of derivational morphemes that are used to create new words or to “make words of a different grammatical class from the stem” (Yule,
2010, p. 69).
For example, the addition of the derivational morpheme -ize changes the
adjective normal to the verb normalize. Similarly, we can derive the adjectives helpful and helpless by adding the derivational morphemes -ful and less to the noun help.
The second type of bound morphemes consists of inflectional morphemes that are used to show some aspects of the grammatical function of a word. We use inflectional morphemes to indicate if a word is singular or plural, whether it is past tense or not, and whether it is a comparative or possessive form.
In fact, inflection exists in many languages, but compared to other languages of the world there is relatively little inflection in English. Today there are only eight inflectional morphemes in English, as
shown in the image below:
Differences between Derivational and Inflectional Morphemes
There are some differences between inflectional and derivational morphemes.
First, inflectional morphemes never change the grammatical category (part of speech) of a word. For example, tall and taller are both adjectives. The inflectional morpheme -er (comparative marker) simply produces a different version of the adjective tall.
However, derivational morphemes often change the part of speech of a word. Thus, the verb read becomes the noun reader when we add the derivational morpheme -er. It is simply that read is a verb, but reader is a noun. However, some derivational morphemes do not change the grammatical category of a word.
For example, such derivational prefixes as re- and un- in English generally do not change the category of the word to which they are attached.
Thus, both happy and unhappy are adjectives, and both fill and refill are verbs, for example. The derivational suffixes -hood and -dom, as in neighborhood and kingdom, are also the typical examples of derivational morphemes that do not change the grammatical category of a word to which they are attached.
Second, when a derivational suffix and an inflectional suffix are added to the same word, they always appear in a certain relative order within the word. That is, inflectional suffixes follow derivational suffixes. Thus, the derivational (-er) is added to read, then the inflectional (-s) is attached to produce readers.
Similarly, in organize– organizes the inflectional -s comes after the derivational -ize. When an inflectional suffix is added to a verb, as with organizes, then we cannot add any further derivational
suffixes. It is impossible to have a form like organizesable, with inflectional -s after derivational -able because inflectional morphemes occur outside derivational morphemes and attach to the base or stem.
For these reasons, Akmajian et al. (2010, p. 46) state that derivational morphemes show the “inner” layer of words, whilst inflectional suffixes mark the “outer” layer of words.
A third point worth emphasizing is that certain derivational morphemes serve to create new base forms or new stems to which we can attach other derivational or inflectional affixes. For example, we use the derivational -atic to create adjectives from nouns, as in words like systematic and problematic.
Then, we can further add -al to these two words to create systematical and problematical. Similarly, the derivational suffix -ize is often added to create verbs from adjectives, as in modernize, and we can add the inflectional suffix -s (modernizes) to such -ize verbs. To sum up, we can state that certain derivational affixes produce new members for a given class of words, but inflectional affixes are always added to available members of a given class of words.
Some Exceptions in English Morphology
As in many languages of the world, English also has some irregularities or exceptions in its morphology. So far, we have only exemplified English words in which various inflectional and derivational morphemes can be simply recognized as distinct minimal units of meaning or grammatical function.
The plural morpheme -s is attached to boy, and the plural boys is created. Although the vast majority of nouns pluralize in English by adding –s, some nouns form their plurals irregularly. Typical examples of such irregular plurals in English are man-men, woman-women, foot-feet, mouse-mice, tooth-teeth, sheep-sheep and deer-deer.
There are also exceptions in the forms of the past tense verbs in English, for example began, broke, went and ran. Both historical influences and the effect of borrowed words play a role in accounting for such irregularities. For pedagogical purposes, most grammar and writing textbooks include long lists of these exceptions in English morphology.