Morphemes, Word Classes, and the Structure of Words

This lesson explains how words are built from smaller meaningful parts and how those parts help us classify words. In 5-Morphology-_words-and-parts-35 (1), morphology is presented as the study of “words and their parts,” with the key idea that speakers have unconscious knowledge of word structure.

1. What is a morpheme?

A morpheme is a piece of a word that expresses its own meaning. According to 5-Morphology-_words-and-parts-35 (1), morphemes are meaningful parts of words, and morphology helps us recognize both actual words and possible words.

For example, a word may contain:

• a root, which carries the core meaning, and
• an affix, which adds meaning or grammatical information.

The source lists affixes such as -ment, -ion, -er, -ing, -s, -able, -ize, -ship, and -ity.

2. Word classes: content words and function words

5-Morphology-_words-and-parts-35 (1) states that words can be divided into two basic classes: content words and function words.

Content words

Content words carry the main meaning of a message. They name things, actions, qualities, or ideas.

• Nouns
• Verbs
• Adjectives
• Adverbs

These are the words most closely tied to the vocabulary stored in our mental lexicon, a topic highlighted in 5-Morphology-_words-and-parts-35 (1).

Function words

Function words do less naming and more grammatical work. The source shows that they are important for structure and agreement. For example, in the Old English examples, forms meaning “this/that” must match the noun’s grammatical features. This shows that function words help organize relationships in a sentence.

Function words include items such as determiners and other grammatical markers that help connect content words.

3. Free and bound morphemes

5-Morphology-_words-and-parts-35 (1) explains that morphemes come in different types, especially free and bound.

Free morphemes

A free morpheme can stand alone as a word.

• Example: happy
• Example: lock

Bound morphemes

A bound morpheme cannot stand alone; it must attach to another morpheme.

• Example: un-
• Example: -ness
• Example: -able
• Example: -s

These bound morphemes are usually affixes.

4. Roots and affixes

A root is the main meaning-bearing part of a word. An affix attaches to a root. In 5-Morphology-_words-and-parts-35 (1), affixes include prefixes, suffixes, and even infixes in some languages.

Prefixes

A prefix comes before the root.

• un + happy → unhappy

The source notes that derivational prefixes in English usually do not change the word class. For example, happy and unhappy are both adjectives.

Suffixes

A suffix comes after the root.

• happy + -ness → happiness

In this case, the suffix changes the category from adjective to noun. As explained in 5-Morphology-_words-and-parts-35 (1), derivational suffixes often create a new word class.

Infixes

An infix is inserted inside a root. The source gives examples from Inuktitut and notes that English has a limited kind of infixation called expletive infixation, used for emphasis.

5. Derivational affixation

Derivational affixation creates new words. It may change meaning, word class, or both.

• happy → unhappy: meaning changes, class stays adjective
• happy → happiness: meaning changes, class changes from adjective to noun

The source also shows that words with derivational affixes are stored as distinct words in the mental lexicon. For example, happy and unhappy are separate entries because they have different meanings.

6. Morphemes and ambiguity

Morpheme structure can affect meaning. 5-Morphology-_words-and-parts-35 (1) gives the example unlockable, which has two possible meanings because the morphemes can combine in two different ways:

• [un [lockable]] = not lockable
• [[unlock] able] = able to be unlocked

This example shows that identifying roots and affixes is not just about form; it also helps explain meaning.

7. How to classify morphemes

To classify a morpheme, ask these questions:

1. Does it have meaning or grammatical function of its own?
2. Can it stand alone as a word?
3. Is it the core meaning part of the word?
4. Does it attach before, after, or inside another morpheme?

Using 5-Morphology-_words-and-parts-35 (1), you can label morphemes like this:

• lock: free morpheme, root
• un-: bound morpheme, prefix, affix
• -able: bound morpheme, suffix, affix
• happy: free morpheme, root
• -ness: bound morpheme, suffix, affix

8. Summary

• A morpheme is the smallest meaningful part of a word.
• Words fall into two broad classes: content words and function words.
• Free morphemes can stand alone; bound morphemes cannot.
• A root carries the core meaning of a word.
• An affix attaches to a root; common types are prefixes and suffixes.
• Derivational affixes create new words and may change word class.
• The structure of morphemes helps explain why words can have different meanings, as in unlockable.

Overall, 5-Morphology-_words-and-parts-35 (1) shows that understanding morphology helps us identify meaningful word parts, distinguish kinds of words, and analyze how words are formed.