According to the guidelines of morphology, the linguistics branch concerned with the internal structure of words, a morpheme is the very smallest meaningful linguistic unit in the grammar of a language. In writing, they are composed of graphemes, or the smallest units of typography. In oral language, however, they are composed of phonemes, or the smallest units of speech. People categorize them according to how they work together and the functions they have, and they usually are combined according to a specific hierarchical structure. Studying them is important because it might show how to speed up learning a language or serve as tool for tracking language shifts.
Application of Definition
The current definition for these elements means that, in terms of length and function, they can be either a word or just an element of a word. For example, the word “technique” is both a word and a morpheme, because it cannot be broken down into any smaller meaningful units. A more complex example is the word “unkindly,” which consists of three parts: “un,” which means not, “kind,” which means benevolent, and “ly,” which means like. None of these can be broken up into smaller parts without losing all semantic meaning.
Many people believe that morphemes are the same as syllables, but this is incorrect. The word “cheddar,” for example, has two syllables, "ched" and "dar." These syllables can't be broken apart, because they have no semantic meaning on their own, so there is only one morpheme.
Some people assert that some larger terms and phrases technically could be classed as morphemes. A good example of this is the common idiom "the last straw," where the idea of having reached a limit isn't conveyed unless all three words appear together. Collocations such as "iron will" are additional instances where getting meaning requires using more than one word.
Categorization
Linguists usually classify morphemes into two main groups based on how they combine to create a word. A "free" or "unbound" morpheme is a linguistic unit that is able to stand alone as a word without anything else attached to it. The word “cat” is a good example.
"Bound" morphemes, on the other hand, are sounds or a combination of sounds that must be bound to a free morpheme in order to create a word. Most prefixes and suffixes are this type. The letter “s” in the word “dogs,” for instance, is bound, because it does not have any semantic meaning without the free part, “dog.” This group is often further broken down into inflectional units, which modify tense or number and show grammatical relationships without changing meaning, and derivational units, which form new words when put together with a root, and which change parts of speech, meaning or both.
In the English language, people also label morphemes as roots, stems, or affixes. A root, sometimes called a base, gives meaning and is the unit to which others attach. As an example, "teach" is a root that can help form words like "teacher." An affix is a morpheme that attaches to either end of a root — prefixes attach at the beginning, while suffixes go on at the end. A stem is the root of a word combined with any affixes.
Structure and Hierarchy
In addition to studying how these units function and what they mean, linguists also look at how they go together, or how they're structured. They assert that, in general, there is a particular order of arrangement, which sometimes is described as being hierarchical. Basically, people usually try to put them together in a way that provides the most sense in terms of meaning as quickly as possible, which often means adding affixes last. When making the word "unspeakable," for example, a person would start by combining "speak" and "able," not "un" and "speak."
Reason for Study
People study morphemes because, according to linguists, they are the heart of communication. The way people use them, either alone or in combination, drastically affects the information that is passed from one person to another. Linguists are not quite sure how people learn to combine them properly according to the rules of particular languages, and they don't know exactly how individuals come to associate specific meanings with exact morphemes, but they hope that looking closely at these elements will provide some clues about language acquisition. This information could be very useful in helping people learn languages faster. It also could help analyze language development as it happens over time.