Morphology is the study of morphemes—the smallest recognizable units in a language. For example, the word cats is comprised of two morphemes—the root word cat and the –s that makes it plural. The word inconceivable contains three morphemes: the root word conceive, the prefix in– and the suffix –able. The word earring is a compound word (a word made up of two or more words) consisting of two morphemes—ear and ring. Knowing something about morphology can help you spell words correctly and determine their meaning without having to crack open a dictionary.
Morphology also applies to the roles that words play in sentences—whether a word functions as a noun, verb, adjective, adverb, or one of the other eight parts of speech described in Chapter 3.
Of course, you can know much more about morphology, including the distinctions between roots, stems, and affixes (such as prefixes and suffixes); free and bound morphemes; and inflectional and derivational morphemes. But such information is of interest only to those working toward a degree in English or linguistics. For the rest of us, knowing about root words, compound words, prefixes, suffixes, and parts of speech is sufficient.