Word formation and grammatical choice
Word formation changes grammatical category and meaning through roots, prefixes and suffixes, which directly affects sentence structure.
01 · Concept foundation
Understand the terms before applying the rule
Each term below names a different grammatical object. Open examples and compare their function rather than memorising a Vietnamese translation alone.
morpheme/ˈmɔːfiːm/
hình vịThe smallest unit of form that carries meaning or grammatical function.
un-certainty, model-s
un-certainty, model-s
derivation/ˌderɪˈveɪʃən/
phái sinhThe creation of a new word, often with a new word class, by adding an affix.
analyse → analysis → analytical
phân tích → sự phân tích → thuộc phân tích
inflection/ɪnˈflekʃən/
biến tốA grammatical change that creates another form of the same lexeme without creating a new dictionary word.
model → models; calibrate → calibrated
model → models; calibrate → calibrated
root/ruːt/
gốc từThe element carrying the central lexical meaning of a word family.
predict in prediction, predictable and unpredictability
predict trong prediction, predictable và unpredictability
affix/ˈæfɪks/
phụ tốA prefix or suffix attached to a base to change meaning or grammatical function.
re-calibr-ation; un-reli-able
re-calibr-ation; un-reli-able
word family/ˈwɜːd fæməli/
họ từA set of established words sharing a root but occupying different grammatical categories or meanings.
analyse, analysis, analytical, analytically, analyst
analyse, analysis, analytical, analytically, analyst
nominalisation/ˌnɒmɪnəlaɪˈzeɪʃən/
danh hóaThe packaging of a process or quality as a noun, common in academic writing but potentially dense when overused.
The coast eroded → coastal erosion
Bờ bị xói → sự xói lở bờ
Complete lesson scope
Do not stop at one formula
Roots, prefixes, suffixes and grammatical morphemes
Noun, verb, adjective and adverb word families
Negative, reversative, degree and evaluative affixes
Conversion, compounding and spelling changes
Decision boundary: A grammatically possible derived form may still be rare or unsuitable for the intended register.
02 · Controlling rule
Analyse prefix, root/base, derivational suffix and inflection separately. Use surrounding grammar to predict the required word class, then verify that the resulting form, spelling, meaning and collocation are established English.
prefix + root/base + derivational suffix + inflectionRoots, affixes and word-family control
Analyse a word into meaningful parts, predict grammatical category from the sentence slot and build or select the correct member of a word family without inventing forms.
1. Morpheme, root, base and stem
A morpheme is the smallest form carrying meaning or grammatical function. A root carries the central lexical meaning; a base is any form to which an affix can be added; a stem is the form to which inflection attaches.
prefix + root/base + derivational suffix + inflectionIn unpredictability: un- + predict + -able + -ity. The root predict carries the lexical core; later suffixes change category.
Derivational affixes create a new lexeme or category; inflection marks grammar without creating a new dictionary word: model → models; calibrate → calibrated.
Not every visible string is a productive affix; verify doubtful forms in a reliable dictionary rather than inventing them.
The recalibration improved the reliability of the sensor network.
Word-class signals
Suffixes are clues, not guarantees. Always verify meaning, spelling and established usage.
| Target class | Common suffixes | Examples |
|---|---|---|
| Noun | -tion, -ment, -ness, -ity, -ance, -er | calibration, development, reliability |
| Adjective | -al, -ive, -ous, -ful, -less, -able | numerical, effective, reliable |
| Verb | -ise/-ize, -ify, -en, -ate | standardise, simplify, widen |
| Adverb | -ly (often) | significantly, reliably, carefully |
Diagnosing the required word class
Read both sides of the gap and identify the grammatical head before choosing a family member.
| Context | Likely class | Example |
|---|---|---|
| determiner + ___ + verb | noun | The analysis shows... |
| ___ + noun | adjective/noun modifier | reliable data; model output |
| modal + ___ | base verb | can improve |
| verb + ___ (manner) | adverb | responded rapidly |
| be + ___ | adjective/noun complement | is reliable; is a limitation |
High-risk contrasts
After an, the sentence needs a singular countable noun; analyse is a verb, analysis is the noun.
After the linking verb is, the sentence describes the subject and therefore needs an adjective.
The word describes how strongly the estimates changed, so use an adverb.
The established negative form is impossible; negative prefixes are not freely interchangeable.
Concept and form check
Apply the system in context
Build a five-member academic word family and use four members in a short IELTS paragraph. Underline the sentence slot that determines each form and avoid unnecessary nominalisation.
- ✓The chosen family member matches the grammatical slot.
- ✓Prefix and suffix forms are established English words.
- ✓Nominalisation improves information flow rather than hiding the action.
03 · Worked examples
Observe form, function and meaning together
The recalibration improved the reliability of the sensor network.
Việc hiệu chỉnh lại cải thiện độ tin cậy của mạng cảm biến.
The revised algorithm significantly improved computational efficiency.
Thuật toán đã sửa cải thiện đáng kể hiệu suất tính toán.
The model underestimated peak discharge because the roughness was overcalibrated.
Mô hình đánh giá thấp lưu lượng đỉnh vì hệ số nhám được hiệu chỉnh quá mức.
The rapid expansion of the network improved spatial coverage.
Việc mở rộng nhanh mạng lưới cải thiện độ phủ không gian.
04 · High-risk contrast
Explain why one form fails, not only which answer is correct
The team completed an analyse of the record.
The team completed an analysis of the record.
After an, the clause needs a singular countable noun. Analyse is a verb; analysis is the noun member of the family.
05 · Mastery check
Apply the rule before marking the lesson complete
Which sentence is grammatically acceptable in the target system?
Which description best defines “morpheme”?
Which example is one of the verified target patterns in this lesson?
Which structural formula belongs to this lesson?
Complete all four checks, then submit a sentence for target-form feedback.
06 · IELTS Academic
Transfer grammar into a real communicative task
Use word families to vary expression and nominalise selectively: analyse → analysis → analytical → analytically, while keeping agents and actions visible when clarity requires them.
Separate derivation from inflection.
Recognise common noun, adjective, verb and adverb suffixes.
Use prefixes according to established meaning rather than inventing forms.
Build a word-family table and use each member in the correct slot.