Grammar & meaning
Learn to split words into meaningful parts, explain what each part contributes, and use a sentence to resolve ambiguous endings.
GUIDED LESSONStart here
Knowing that a word has a prefix is less useful than knowing what the prefix does. This lesson starts with paint, repaint and painters, then shows why “cleaner” needs a sentence before you can analyse it.
By the end: Explain a prefix, root and suffix in a familiar word, and distinguish making a new word from adding grammatical information.
What you need: The English sentences below and a few lines of notes. No formal grammar course or separate text collection is required.
Before you begin: No formal grammar knowledge needed. Work with the English examples here before comparing another language.
How to work through this lesson
- Read the short definitions, then compare one change at a time: paint → repaint; paint → painter; painter → painters.
- Follow the worked sentences. Write what each added part contributes instead of cutting words wherever the letters happen to repeat.
- Analyse “repainted” and both meanings of “cleaner”, then check your reasoning against the explained answers.
Start with meaning, then find the parts
Compare paint with repaint. The second word still involves painting, but re- adds the idea of doing it again. Compare painter with painters: -s marks more than one painter. These pieces have jobs, rather than merely being repeated letters.
- Morpheme
- A smallest word part associated with meaning or grammatical function. A morpheme need not be a whole word or a syllable.
- Root or base
- The material an operation builds on. Paint is the root in these examples; painter is the base to which plural -s is added.
- Prefix and suffix
- An attached part before its base is a prefix, such as re-. One after its base is a suffix, such as -er. Both are affixes.
- Inflection and derivation
- Inflection adds grammatical information, such as plural number. Derivation makes a new lexical item, such as painter from paint.
Worked example: from paint to painters
Use a sentence so the intended meaning is clear: “The painters arrived.” We are analysing the people who paint, not guessing from an isolated string of letters.
| Form | Analysis | Contribution |
|---|---|---|
| paint | paint | Base verb in these comparisons |
| repaint | re- + paint | Paint again |
| painter | paint + -er | A person who paints; a noun |
| painters | painter + -s | More than one painter |
Find a related base.
Painter has the related verb paint, and its meaning is connected. That gives a reason to propose paint + -er.
Explain the added part.
Here -er makes a person noun from the verb. This is derivation. In painters, the added plural -s supplies grammatical number: this is inflection.
Check the pattern in another word.
Compare teach → teacher → teachers. The spelling is not identical at every boundary in every English word, but the relevant person-noun and plural functions recur here.
Test a tempting wrong cut.
The word red begins with the letters re, but that does not give it the “again” prefix. There is no relevant base d that means the activity being repeated.
One ending can have more than one job
“The cleaner arrived” uses cleaner as a person noun: someone who cleans. “This cup is cleaner” uses cleaner as a comparative adjective: more clean. The written ending -er occurs in both, but the sentence tells you which job it is doing.
For each proposed part, ask what it contributes in this sentence and what comparison supports that analysis. Do not assume every matching sequence has the same history or present-day function. This lesson analyses contemporary English patterns; a word’s etymology is a separate question.
Try it yourself
Write your answer before opening the explanation. Use the worked example if you get stuck.
Question 1
Analyse repainted in “Yesterday we repainted the door.” Name the base and the job of each added part.
Show answer and reasoning
re- + paint + -ed. Paint is the base verb; re- adds “again”; -ed marks the past tense in this sentence. The past-tense context matters because an -ed form can have other grammatical uses in other sentences.
Question 2
Compare “The cleaner arrived” and “The cup is cleaner.” Why is “-er means a person” an incomplete rule?
Show answer and reasoning
The first sentence has a person noun derived from clean as a verb. The second has the comparative adjective, meaning more clean. The same spelling does not force the same grammatical function; use the sentence and related forms as evidence.
Question 3
In “Two teachers waited”, which suffix makes the person noun and which marks plural number? Give another form that supports the analysis.
Show answer and reasoning
Teach + -er gives teacher, a person noun. Teacher + -s gives teachers, marking plural number. Compare one teacher with two teachers; the change in number supports the plural analysis. Teacher remains a noun in both cases.
Summary + next step
- Explain the contribution of a proposed part; do not merely draw boundaries.
- Use related forms to support the analysis.
- Read the sentence when one spelling allows more than one grammatical interpretation.
Keep the result: Keep an analysis in this form: word in a sentence → parts → contribution of each part → evidence from another word.
Sources and further reading
MIT lecture 2 explains roots and affixes. The inflection chapter gives more examples of grammatical information expressed through word structure; follow it after completing the English comparisons here.
- MIT 24.900: morphology, lecture 2 ↗
- Essentials of Linguistics, 2nd edition: inflectional morphology ↗
Lesson updated 2026-10-22 · Guidance updated 2026-10-22
Coverage and further development
Explain a prefix, root and suffix in a familiar word, and distinguish making a new word from adding grammatical information.
Further development: Sentence structure, agreement, semantic scope and pragmatics, with language-specific comparisons beyond this word-structure lesson.