3.1 Derivational morphology and word formation

Understanding Derivational Morphology

Derivational morphology is the process of creating new words from existing ones by adding affixes (prefixes and suffixes). When you attach a derivational affix to a word, you can change its meaning, its part of speech, or both.

This matters because it's the foundation for understanding how English vocabulary expands. It also sets up a key distinction you'll need throughout this unit: the difference between derivational and inflectional morphology.

Definition of Derivational Morphology

Derivational morphology is the branch of morphology that focuses on word formation, the process of building new words from existing ones. It works by adding affixes to a base word, which can:

• Change the word's class (its part of speech)
• Alter the word's meaning
• Or do both at once

Here are some clear examples of class changes:

• Noun → Adjective: beauty → beautiful
• Verb → Noun: sing → singer
• Adjective → Adverb: quick → quickly

Each of these produces a genuinely new word (a new lexeme), not just a different grammatical form of the same word. That distinction is what separates derivation from inflection.

Common Derivational Affixes

Prefixes attach before the base word and typically modify its meaning without changing its word class:

• un- negates the meaning (happy → unhappy, both adjectives)
• re- indicates repetition (do → redo, both verbs)
• pre- means "before" (historic → prehistoric, both adjectives)

Suffixes attach after the base word and often do change the word class:

• -able / -ible creates adjectives meaning "capable of being" (read → readable)
• -tion / -sion forms nouns indicating a state or process (educate → education)
• -ize creates verbs meaning "to make or become" (computer → computerize)

Notice the pattern: prefixes tend to change meaning while keeping the same part of speech, and suffixes tend to shift the word into a different part of speech. This isn't an absolute rule, but it holds for most common English affixes.

Analyzing Word Structure and Morphology Types

Structure of Derived Words

When you break down a derived word, follow these steps:

1. Identify the base word (the root or stem that carries the core meaning).
2. Locate any prefixes attached before the base.
3. Locate any suffixes attached after the base.
4. Check for multiple affixation, where prefixes and suffixes stack onto the same base.

Take the word unforgettable: the base is forget, the prefix un- adds negation, and the suffix -able turns it into an adjective. The structure is un- + forget + -able.

Words can also involve compound derivation, where two bases merge and then take affixes. For example, blackboard is a compound, and blackboard-er (if it existed) would be a compound with a derivational suffix.

Derivational vs. Inflectional Morphology

This is one of the most important distinctions in the unit. Both processes use affixes, but they do very different things.

Compare these two:

• teach → teacher (derivational: new word, new class — verb became a noun)
• teach → teaches (inflectional: same word, same class — verb stays a verb, just marked for third-person singular)

A few more differences to keep straight:

• Derivational affixes can be either prefixes or suffixes. In English, inflectional affixes are almost always suffixes.
• Derivational affixes attach closer to the base. Inflectional affixes go on the outside. That's why you get teachers (derivational -er first, then inflectional -s), never teach-s-er.
• English has only about eight inflectional suffixes (-s, -ed, -ing, -en, -s, -'s, -er, -est), but hundreds of derivational affixes.