Spelling Rules and Common Errors

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In 30 seconds

Rules: i before e except after c; double final consonant before -ing/-ed in short stressed words; drop final silent e before vowel-suffix; change y → i before suffix.
CDS pattern: 4 options where 3 are misspelt - pick the correct one. Or one wrong spelling embedded in a sentence.
Spell-bombs: Words frequently misspelt in CDS - accommodate, occurrence, conscience, embarrass, millennium, supersede, etc.

Spelling questions test memory of high-frequency spelling traps. The CDS examiner draws from a stable pool of ~150 difficult words. Master the rules and the high-yield list and this section yields easy marks.

Core Spelling Rules

Rule	Example	Exceptions
'i' before 'e' except after 'c' (when sound is /ee/)	believe, achieve, retrieve / receive, deceive, ceiling	seize, weird, foreign, neighbour, weight (sound not /ee/)
Drop final silent 'e' before a vowel-starting suffix	hope + ing = hoping; love + able = lovable	noticeable, manageable (keep 'e' to retain soft c/g sound)
Keep final 'e' before consonant-starting suffix	hope + ful = hopeful; love + ly = lovely	argue + ment = argument; true + ly = truly
Double final consonant in short stressed syllables before vowel-suffix	stop → stopping; run → running; begin → beginning	visit → visiting (stress on first syllable, no doubling)
Change y → i before suffix (when y follows consonant)	happy + ness = happiness; carry + ed = carried; beauty + ful = beautiful	Keep y before -ing: carry + ing = carrying. Keep y after vowel: play + ed = played
Plural: -s usual; -es after s, x, z, ch, sh; -ies after consonant + y	cats, boxes, churches, ladies	roof → roofs (not rooves); knife → knives

Most-Misspelt CDS Words

Correct spelling	Common misspelling
accommodate	accomodate (double c, double m)
occurrence / occurred	occurence / occured (double c, double r)
achievement	acheivement (i before e)
acquaintance	aquaintance (cq, not q)
address	adress (double d)
aggression	agression (double g)
argument	arguement (drop the e)
beginning	begining (double n)
believe	beleive (i before e)
business	buisness (u-s-i not u-i-s)
calendar	calender (-dar, not -der)
cemetery	cemetary (three e's, not -ary)
changeable	changable (keep the e)
committee	commitee / comittee (double m, double t, double e)
conscience	concience / conscence
conscientious	conscientous
definitely	definately (-nite-, not -nate-)
disappear	dissapear (single s, double p)
disappoint	dissapoint (single s, double p)
embarrass	embarass (double r, double s)
environment	enviroment (n before m)
existence	existance (-ence, not -ance)
foreign	foriegn (e before i)
government	goverment (keep the n)
grammar	grammer (-ar, not -er)
harass	harrass (single r, double s)
independent	independant (-ent, not -ant)
knowledge	knowlege (keep the d)
liaison	liason (two i's)
maintenance	maintainance (-tenance, not -tainance)
millennium	millenium / milennium (double l, double n)
necessary	neccesary / necessery (single c, double s)
occasion	occassion (double c, single s)
parallel	parralel (single r, double l in middle)
perseverance	perseverence (-ance, not -ence)
possession	posession (double s twice)
privilege	priviledge / privelege
questionnaire	questionaire (double n)
receive	recieve (after c → e before i)
recommend	reccomend (single c, double m)
referred	refered (double r)
rhythm	rythm / rhythym (h after r, no vowel)
separate	seperate (-par-, not -per-)
supersede	supercede (-sede, the only -sede word)
tomorrow	tommorow (single m, double r)
weird	wierd (e before i)

Tricky Plurals

Singular	Plural
child	children
foot	feet
tooth	teeth
man / woman	men / women
mouse	mice
goose	geese
ox	oxen
sheep / deer / fish / aircraft	same (no change)
criterion	criteria
phenomenon	phenomena
medium	media
datum	data
radius	radii
fungus	fungi
cactus	cacti
thesis	theses
crisis	crises
analysis	analyses
basis	bases
oasis	oases
parenthesis	parentheses
knife / wife / life	knives / wives / lives
leaf / loaf	leaves / loaves
chief / roof	chiefs / roofs (no change to v)