Grammar / usage: Word formation — prefixes and suffixes
Subtopic: Section D · Grammar
How to structure your answer
Rule: new English words are typically formed by attaching a prefix (added at the front, usually changing meaning) or a suffix (added at the end, usually changing the part of speech). Knowing the productive families — negative prefixes ('un-', 'in-', 'im-', 'il-', 'ir-', 'dis-', 'non-'), and noun-forming suffixes ('-tion', '-ment', '-ity', '-ness'), verb-forming suffixes ('-ise/-ize', '-ify', '-en') and adjective-forming suffixes ('-able', '-ful', '-less', '-ous') — helps both reading speed and writing precision.
Approach: identify the base word's part of speech; decide what part of speech is needed; choose a suffix that performs that transformation. For negation, the choice between 'un-', 'in-', 'im-', 'il-', 'ir-' is partly determined by the first letter of the base ('il-' before 'l', 'ir-' before 'r', 'im-' before 'b/m/p').
What an examiner expects: the rule stated cleanly; correct forms supplied for prompts (verb to noun, adjective to noun, noun to adjective); a one-line justification.
Common pitfalls: (1) using the wrong negative prefix ('unpossible' instead of 'impossible'); (2) doubling consonants incorrectly when adding suffixes; (3) confusing '-ic' and '-ical' adjectives (economic vs economical).
Written within the word limit
94 words · target 100 words · 8 min
Rule: A prefix attached to a base word modifies meaning (un-, dis-, re-, pre-, mis-); a suffix attached to a base word changes grammatical class (-ness, -ity, -tion, -able, -ly).
Worked examples: Happy → unhappy (negation by prefix); happy → happiness (noun by suffix); govern → misgovern, government, governable. Prefixes seldom change part of speech; suffixes usually do.
Quick check:
- The opposite of visible is ____. invisible
- The noun form of create is ____. creation
- Add a prefix to read to mean 'read in advance': ____. preread
- The adjective form of respond is ____. responsive (or responsible)
- The adverb form of quick is ____. quickly
What an examiner expects to see
- Prefix: added at the front, changes meaning (usually).
- Suffix: added at the end, changes part of speech (usually).
- Negative prefixes: un-, in-, im- (before b/m/p), il- (before l), ir- (before r), dis-, non-.
- Verb → noun: -tion (educate → education), -ment (achieve → achievement), -ance (perform → performance), -al (refuse → refusal).
- Adjective → noun: -ity (able → ability), -ness (kind → kindness), -ce (silent → silence).
- Noun/adjective → verb: -ise/-ize (modern → modernise), -ify (simple → simplify), -en (broad → broaden).
- Noun → adjective: -ful (care → careful), -less (hope → hopeless), -ous (danger → dangerous), -al (form → formal), -ive (act → active).
- Adjective → adverb: -ly (quick → quickly); some adjectives end in -ly already (friendly, lovely).
- Spelling rules: drop final -e before -ing/-able/-ous (use → using, value → valuable); double final consonant after short stressed vowel (run → running).
- Practice prompts for the examinee.
Concrete cases, schemes and judgments
- Verb to noun: 'develop' → 'development'; 'analyse' → 'analysis'; 'apply' → 'application'.
- Adjective to noun: 'happy' → 'happiness'; 'curious' → 'curiosity'; 'efficient' → 'efficiency'.
- Negation: 'possible' → 'impossible' (im- before p); 'legal' → 'illegal' (il- before l); 'regular' → 'irregular' (ir- before r); 'happy' → 'unhappy'.
- Wrong: 'unpossible'. Right: 'impossible'. (Negative prefix before 'p' is im-.) Wrong: 'economical growth'. Right: 'economic growth'. (-ic for relating to economy; -ical for thrifty.)