Spelling & Commonly Confused Words

Why spelling matters

Spelling-correction questions ask you to find the correctly or incorrectly spelt word. Errors come from a few sources: silent letters, doubled letters, vowel confusions (-able / -ible, -ance / -ence), ie/ei, and borrowed words. The good news is that a small set of rules and a list of about 150 words cover most questions.

Core spelling rules

1. "i before e, except after c" (when the sound is /ee/)

• ie: believe, achieve, field, piece, relief, thief, brief, chief, grief, niece, siege, retrieve.
• ei after c: receive, receipt, deceive, conceive, perceive, ceiling.
• Exceptions: seize, weird, either, neither, leisure, protein, caffeine, species, science.
• ei when the sound is not /ee/ (like ay): neighbour, weigh, eight, freight, reign, vein, sleigh.
• Words with "ie" after c sound /sh/: ancient, efficient, sufficient, conscience, science.

2. Doubling the final consonant

When adding a suffix that begins with a vowel (-ed, -ing, -er) to a word:

• One syllable, consonant–vowel–consonant (CVC) ending → double: stop → stopped, run → running, big → bigger, plan → planned.
• Two syllables, stress on the last syllable → double: begin → beginning, refer → referred, occur → occurred, admit → admitted, prefer → preferred.
• Stress on the first syllable → do not double: visit → visited, offer → offered, open → opened, benefit → benefited, develop → developed.
• Do not double if the word ends in two consonants or two vowels + consonant: help → helping, wait → waiting.
• Words ending in l (British): travel → travelled, cancel → cancelled, model → modelled (American: traveled).

3. Silent e

• Drop the e before a suffix beginning with a vowel: make → making, hope → hoping, love → lovable, write → writing.
• Keep the e before a suffix beginning with a consonant: hope → hopeful, love → lovely, care → careful, manage → management.
• Keep the e after c or g to preserve the soft sound before -able/-ous: notice → noticeable, manage → manageable, courage → courageous, change → changeable.
• Exceptions: argue → argument, true → truly, judge → judgment (judgement), whole → wholly.

4. Words ending in y

• Consonant + y → change y to i before a suffix (except -ing): happy → happiness, carry → carried, study → studies, beauty → beautiful, easy → easily. But carry → carrying, study → studying.
• Vowel + y → keep y: play → played, enjoy → enjoyed, key → keys, day → days.
• Exceptions: pay → paid, say → said, lay → laid.

5. Plurals

• Add -s: books, bridges. Add -es after s, x, z, ch, sh: boxes, churches, classes.
• Consonant + o: heroes, potatoes, tomatoes, echoes; but photos, pianos, radios, videos, zeros/zeroes.
• Consonant + y → -ies: city → cities.
• -f/-fe → -ves: leaf → leaves, knife → knives, wife → wives, life → lives; but roofs, chiefs, proofs, beliefs.
• Irregular: man/men, woman/women, child/children, tooth/teeth, foot/feet, mouse/mice, person/people.
• Latin and Greek plurals: datum → data, criterion → criteria, phenomenon → phenomena, crisis → crises, analysis → analyses, basis → bases, medium → media, curriculum → curricula, syllabus → syllabi/syllabuses, formula → formulae/formulas.

6. Prefixes and suffixes

• Adding a prefix does not change the spelling of the root: un + necessary → unnecessary, dis + appear → disappear, mis + spell → misspell, im + mortal → immortal, in + numerable → innumerable.
• -ful is spelt with one l: careful, useful, beautiful, grateful. -ly after -ful → carefully.
• -able vs -ible: -able is more common and is added to whole words (comfortable, readable, adjustable). -ible is added to word roots (visible, possible, flexible, eligible, responsible, accessible, permissible, sensible).
• -ance/-ant vs -ence/-ent: attendance, appearance, importance, resistance, assistance, tolerance vs absence, existence, intelligence, permanent, independent, difference, confidence, evidence.
• -ise vs -ize: British -ise (organise, realise); American -ize. Some words always end in -ise: advertise, advise, comprise, compromise, devise, disguise, exercise, improvise, revise, supervise, surprise.

Commonly misspelt words

Double letters

Vowels and other letters