Spelling Rules and Common Errors

Why spelling is a guaranteed scoring area

In the CDS English paper, vocabulary-based questions form a steady chunk of the 120 marks, and ‘spotting the correctly or incorrectly spelt word’ appears almost every year. Unlike comprehension or grammar, these questions are fully objective: a word is either spelt right or it is not. There is no interpretation, no trap of tone or context, and no two examiners would disagree on the answer.

That makes spelling one of the highest return-on-effort topics in the paper. A candidate who has revised the standard rules and the commonly confused words can lock in two to four marks in under a minute, leaving more time for the reading-heavy comprehension and cloze sections that genuinely eat into the clock.

The catch is that spelling cannot be reasoned out from scratch in the exam hall—English spelling is famously irregular because it absorbs words from Latin, Greek, French and Old English, each carrying its own conventions. So the winning approach is twofold: learn the handful of rules that do hold most of the time, and memorise the specific high-frequency words where those rules break down. This page gives you both.

The ie / ei rule and its exceptions

The most famous English spelling rule is “i before e, except after c”—but the short version is incomplete. The full, reliable form adds a condition: it applies only when the sound is a long ‘ee’. That clause about the sound is exactly what keeps the rule from misfiring on words such as weigh, neighbour or height, where the vowel is not an ‘ee’ at all.

• i before e: believe, achieve, friend, piece, relief, niece, thief.
• ei after c: receive, deceive, ceiling, perceive, conceit.

When the vowel sound is not ‘ee’ but rather ‘ay’ or ‘eye’, the spelling is usually ei: neighbour, weigh, freight, vein, reign, height.

In the exam, train yourself to first ask: does this word make the long ‘ee’ sound? If yes, the rule applies and you check whether a c precedes the pair. If the sound is ‘ay’ or ‘eye’, lean towards ei. This two-step check disposes of the majority of ie/ei options you will ever see.

Adding suffixes: drop, keep or double

Many spelling errors come not from the root word but from how it joins a suffix (-ing, -ed, -ous, -able, -ly).

Silent final ‘e’

• Drop the e before a suffix starting with a vowel: hope → hoping, write → writing, use → usable.
• Keep the e before a suffix starting with a consonant: hope → hopeful, care → careless, move → movement.
• Keep the e after soft c or g to preserve the sound: noticeable, courageous, manageable.

Final ‘y’

• Consonant + y → change y to i: happy → happiness, beauty → beautiful, carry → carried.
• Vowel + y → keep y: play → played, enjoy → enjoyment, obey → obeying.
• Keep y before -ing: carry → carrying, study → studying (never two i’s).

These three habits—handling the silent e, the final y, and the doubling that follows—cover the vast majority of suffix-based spelling errors. Practise by taking a base word like ‘rely’ and writing all its forms: relies, relied, relying, reliance, reliable. Notice how the y changes to i except before -ing. Drilling families of forms is far more effective than memorising isolated words.

The consonant-doubling rule

Knowing when to double the final consonant before -ing, -ed or -er decides spellings such as occurred, beginning and preferred.

Double the final consonant when ALL of these are true:

• the word ends in a single consonant,
• preceded by a single vowel, and
• the stress falls on the last syllable (or it is a one-syllable word).

So: stop → stopped, run → running, begin → beginning, prefer → preferred, occur → occurrence.

Do not double when the stress is not on the last syllable: benefit → benefited, open → opening, travel → traveled/travelled (British keeps the double l: travelled).

This is why ‘begin’ becomes ‘beginning’ (stress on -gin, so double the n) but ‘listen’ becomes ‘listening’ (stress on lis-, so no doubling). The stress test is the part candidates forget, and it is exactly what CDS exploits with pairs like ‘preferred’ versus ‘preference’—the same root, but the second shifts its stress and so loses the double r.

High-frequency double-letter traps

A large share of CDS spelling errors involve getting the number of double letters wrong. Burn this list into memory:

• accommodate — two c’s and two m’s.
• committee — two m’s, two t’s, two e’s.
• necessary — one c, two s’s (trick: one Collar, two Socks).
• embarrass — two r’s, two s’s.
• occasion — two c’s, one s.
• millennium — two l’s, two n’s.
• possession — four s’s in all (po-ss-e-ss-ion).
• parallel — one r, then two l’s, then one l.

Silent letters and unusual spellings

Words borrowed from Greek, Latin and French carry silent letters that are easy to drop in a hurry.

• Silent g: foreign, sovereign, campaign, resign.
• Silent h: rhythm, rhetoric, exhibition, ghost.
• Silent p: psychology, pneumonia, receipt.
• Silent b: doubt, subtle, debt, plumber.
• Silent c: scissors, scene, fascinate.

Also watch endings that sound the same but are spelt differently: -cede / -ceed / -sede. Only supersede uses -sede; only exceed, proceed, succeed use -ceed; the rest use -cede (precede, recede, concede, intercede).

The safest way to handle silent letters is to learn the words in small themed clusters, as above, rather than meeting them one by one. When you see an option that ‘sounds right’ but looks too short, suspect a missing silent letter—‘goverment’ for government or ‘enviroment’ for environment are textbook traps that rely on you trusting the spoken form over the written one.

British vs American endings

CDS is set in British English, so prefer British spellings when both appear as options.

• -our not -or: colour, honour, favour, behaviour, labour.
• -re not -er: centre, metre, theatre, fibre.
• -ise / -yse commonly: organise, realise, analyse (American uses -ize/-yze).
• -ence not -ense for nouns: defence, offence, licence (noun).

Confusable words that look like spelling errors

Some ‘spelling’ questions are really about choosing the right word, where each spelling is valid but means something different. These overlap with paronyms and homophones.

• stationary (not moving) vs stationery (paper, pens). Trick: stationery has an ‘e’ like pen.
• principal (head of college; chief) vs principle (a rule). The principal is your pal.
• complement (complete) vs compliment (praise).
• practice (noun) vs practise (verb) in British usage.
• its (possessive) vs it’s (it is).

These pairs blur the line between spelling and vocabulary, which is precisely why examiners like them. Both words are correctly spelt in the abstract, so the only way to answer is to know which meaning the sentence demands. Keep a running list of such pairs and attach a one-word memory hook to each, as shown above, so the right form springs to mind instantly.

Worked example: solving a spelling question

Let us walk through a typical CDS ‘pick the correctly spelt word’ item and the reasoning a trained candidate uses.

Notice the method: instead of staring at all four, you fix the rule for the root word (two c’s, one s) and then eliminate. This is faster and safer than comparing options letter by letter.

Twenty words CDS candidates most often get wrong

Revise this consolidated hit-list the night before the exam. The correct spelling is given; cover it and test yourself.

• definitely (not ‘definately’)
• separate (not ‘seperate’)
• maintenance (not ‘maintainance’)
• privilege (not ‘priviledge’)
• liaison, liaise (the order l-i-a-i-s)
• conscience, conscientious
• occurrence (two r’s)
• questionnaire (two n’s)
• guarantee (g-u-a-r)
• mischievous (not ‘mischievious’)
• pronunciation (not ‘pronounciation’)
• government (the silent n: govern-ment)
• February (the first r)
• colleague, league
• exaggerate (two g’s)
• rhythm (no vowels but y)
• acknowledgement
• bureaucracy
• hierarchy
• tendency (not ‘tendancy’)

Do not just read this list—test yourself actively. Cover the word, attempt to write it, then check. The few you get wrong are the ones worth revisiting the next day. Active recall of a short, personalised error list beats passively re-reading a long generic one, and it is how strong candidates convert spelling from a weakness into easy marks.

Previous-year style practice

Practise by collecting every spelling option you misjudge into a personal list and re-reading it before the next test. Spelling improves through controlled repetition, not last-minute reading.

Quick revision

With these rules and lists revised, spelling questions move from a gamble to reliable, fast marks—exactly the kind of edge that lifts your CDS English score.