Consonant doubling is the biggest English spelling problem

     It causes more spelling errors than any other spelling difficulty.                
     In root words of more than one syllable it is totally unpredictable.

                                    
Doubling a consonant is supposed to show that a vowel is short rather than long, as in

                     bitter – biter,  teddy -  tedious,  tinny – tiny

It was intended to apply just to stressed vowels. This is meant to explain why   'conferred' and 'committed' have rr and tt in the past tense, but 'entered' and 'plummeted' don't (when –ed is added to 'confer, commit, enter' and 'plummet').

Unfortunately, English consonant doubling is used very inconsistently. There is no reliable rule for deciding whether to double a consonant, or not, in similarly sounding words. Learners have to memorise, word by word, when to double and when not to, as the chart below summarises.

               This rote-learning burden of 913 words defeats many learners.

Another 73 words exacerbate it even further.

49 words have unpredictable final -ff, -ll and –ss (if – stiff, stole - poll,  bus – fuss)
and
24 words don't follow the –ccle pattern, of endings like apple,  bubble, tussle,
                                                           for example, chapel, double,  rustle.

Table 1: 379 common words which obey the consonant doubling rule,
               376 words which disobey the doubling rule,
               158 words that have doubled consonants for obscure reasons and
               73 words with unpredictable endings.

Doubled
Letters
 

Words that obey the doubling rule
 

Words that disobey the doubling rule
 

Words with phonically surplus
doubled consonants
(and underlined stressed vowels)

bb







 

abbey           rabbit
cabbage        Sabbath
jabber           shabby

ribbon

hobby            lobby
chubby          stubborn
rubber           stubby rubbish

cabinet         elaborate
cabaret         fabulous
cabin             habit
nebula          treble
liberal           liberty
tribute
probable         robin


 

abbreviate








 

ck

(for cc
  or kk)















 

bracken         packet
bracket         jacket
package        racket

                   reckon




bicker           sticky
chicken         ticket
cricket           wicked
flicker           wicker
rickety          wicket
cockerel         locket
crockery        rocket hockey           rocky
jockey           socket
pocket           stocking
                   bucket cuckoo         sucker

accurate        lacquer
tobacco
vacuum

recognise       decade
record          executive
(noun)
second          echo
secular         mechanism
                   chequered
piccolo
liquor
liquorice

crocodile
documents
occupy



succulent

accomodate               accordion
accommodation         account
accompany                accumulate
accomplish                 accuse
accord                     accustom









occasion
occupation
occurrence



 succumb

dd













 

adder           daddy
caddie           ladder
caddy
                   eddy
                   teddy
                   wedding




giddy            ridden
hidden
shoddy          sodden

rudder           sudden
shudder         pudding

academy        radical
adequate       radish

credit             medical
dedicated         meadow
edible             pedal
edit               pedigree
educate            ready
federal             steady
  already
hideous           video

body              modern
produce          modest
study
 

add









midday

odd


 

ff









 

daffodil           scaffold traffic
                     effigy
                     effort
different
difficult            jiffy
coffee             coffin
offer               office
buffalo            ruffian
buffer             suffer buffet             suffocate
chuffed

cafe

refuge            heifer
refuse (noun)
magnificent
significant

profit



 

affair                            affection
affect                           afford
                                   paraffin
effect
efficient                        effluent
differential
diffusion
offend
official
sufficient

chaffeur

gg





 

baggage        scraggy
jagged           stagger
maggot         swagger
                   beggar
snigger         trigger
soggy
luggage          rugged
nugget

agony            hexagonal
dragon
flagon
negative
brigand          frigate


 

aggravate
aggressive





 

dg
(for j sound)





 

                   badger
                   fledgling


                   midget

dodgy            dodgems
podgy
budgie           drudgery
budget

exaggerate
legend          register
legislate         vegetable
regiment
pigeon            rigid
religion
logic


 

suggest
(pronounced in US)

ll












































 

alley             gallon alligator         gallop
ally              gallows ballast          mallet ballet           rally
ballot           shallow challenge       stallion gallant          valley gallery

swallow         wallop wallaby          wallow wallet
bellow           jelly
belly              pellet cellar             rebellion cello              sellotape cellophane     trellis fellow           umbrella intelligent      yellow


armadillo        illustrate artillery          milligrams billiard           million billion            pillar billow             pillow billy              silly brilliant           vanilla frilly              villa gorilla            village guerillas         villain guillotine        syllable collar             jolly colleague        lollipop college            lolly collie             mollusc colliery           pollen dollar             pollinate follow             trolley hollow             volley holly
lullaby            sullen bullet             bullock bulletin           bully bullion            pulley                         pullover

analysis         reality balance         salad battalion        salary calendar        salon chalet           talent galaxy          talon
italic             valentine morality        valiant palace          valid palate          value palette         vitality


celery              jealous delegate        melody delicacy          melon deluge            pelican develop         relevant element          relic
eligible           skeleton helicopter      telescope                         zealous ability
bilious
military

ventriloquist





cylinder
abolish          polythene colony            quality column          solemn demolish        solid holiday           tolerate olive              volume knowledge     voluntary policy
politics          colour




 

llama
parallel

really









excellent
hello
jewellery
marvellous
satellite
constellation



caterpillar
illegible
illiterate
illusion
illustration
illuminate
pastille
tonsillitis



collage
collapse
collect
collide

controlled
roller
swollen





 

mm




















 

ammonite      mammal clammy        mammoth hammer       stammer inflammable
                   dilemma





glimmer         simmer
                   symmetry

comment      common commentarycommunism commerce   communist



dummy          summer mummy          summit rummage        summon summary        tummy

amateur        dynamic camel           enamel camera        famished damage        laminate
cemetary      remedy chemical       lemon democrat      feminine emerald        premise epidemic       semi memory
criminal         timid eliminate      image
limit
abominable   economic comet           prominent comic           promise dominate      vomit domino




 

ammunition
programme*








immediate              immortal immense                immune

accommodation       commotion command               communication commemorate         communion commence              community commercial              commuter commit                  committee commodities           recommend


 

nn
























 

annual          nanny banner         pannier cannot         savannah granny          spanner manner         uncanny


antenna        tennis
pennant        penny



dinner
inner
innocence
innocent
spinnaker



bonnet         sonnet





 

animal           organic anorak           panel banish          panic banister        spaniel canopy          vanish manage        manual manor
benefit
any              many enemy          penetrate energy         venison menace        lieutenant aluminium      linear cinema        minimal clinical         minister cynical         minute synagogue   opinion synonym       sinister continue       spinach finish            vinegar astonish        monastery conifer         monarch economy      monument electronic     supersonic tonic
honey           onion money

anniversary
announce
annoy

















connect
personnel

mayonnaise

questionnaire
 

pp













 

appetite        happy happen         nappy


pepper

flipper           skipper kipper           slippers

copper         poppy coppice        sloppy opposite


puppet         supper puppy          upper

rapid             capital tapestry        capitol capita          chapel

leper             epic
tepid             separate



copy            topic opera            popular operate        tropics proper
property

 

appal                      applaud apparatus                apply apparent                 appoint appeal                    appreciate appear                    apprentice appendix                 approach                                   appropriate hippopotamus            approve                                     approximate opportunity
oppose



supply                     suppose support

rr






























 

arrow           marrow
barren         marry
barrier          narrative
barrister      narrow
barrow         parrot
carrot         quarry
carry          sparrow
garret         warrant
                   warren
berry          merry
cherry          sherry
errand          terrace
error           terrible
ferry            territory
herring          terror
interrogate


irritable         squirrel
mirror           stirrup


borrow         sorrow
corridor         sorry
horrible         tomorrow
lorry            torrent


                   worry
burrow           hurricane
current          hurry
furrowed       scurry
furry            turret

Arab             caricature
arable           carol
arid             clarity
asparagus     comparison
baron           garage
caramel         parasol
caravan         parish
chariot        transparent
charity
beret             America
  bury            merit
ceremony      peril
cherish          perish
derelict          sincerity
herald            sterilise
heritage        therapist
heroine         very
heron
conspiracy      spirit
empirical         syrup
lyric               tyranny
miracle
authority        laurel
coral             majority
florist            minority
forest            moral
historic           orange
horoscope       priority
                   quarantine

thorough
courage
nourish

arrange
array
arrest
arrive
barricade




erratic
interrupt
serrated
terrific





irregular
irrigation


torrential
correspond
correct
correlation



hurrah
curriculum
surrender
surround

ss















 

ambassador   massive
casserole
classic           passage
massacre       passenger


delicatessen   message
essay           necessity
essence         professor
lesson
missile
narcissus
rissole


blossom         gossip
colossal         possible fossil

acid               glacier
capacity    (US glaishier)
fascinate
pacifist


adolescent      recipe
convalescence specify
crescent          specimen
decimal
chrysalis       participate
discipline         precipice
electricity        publicity
explicit           simplicity
municipal           solicitor
velocity
  sausage
 

assail                     assessment
assassin                   assign
assault                     assist
assemble                 associate
assert                       assort
                               assume
dessert                     cassette
essential                    embassy
necessary
possess
possibility






 

tt



























 

attic             matter
attitude          patter
batter           pattern
battery          regatta
chatter           scatter
clatter           shatter
fatty              tatter
                     latter
better             letter
confetti          lettuce
jettison           pretty
jetty              spaghetti

bitten             mitten
bitter             sitter
glitter             titter
kitten             twitter
litter               written

bottom           lottery
cottage          motto
cotton           otter
forgotten       potter

butter           putty
button           shutter
clutter           splutter
gutter           stutter
mutter           utter mutton

atom             platinum
baton           platypus
catalogue       satin
catapult        strategy
category
compatible
lateral
latitude
athletic           tetanus
magnetic         veteran
metal             yeti
petal           competitive

British              literally
citizen             obliterate
city
critical
pity

botany









 

attach                     battalion
attain
attempt                  tattoo
attend                     mattress
attention
attorney
attract
attributed
omelette
palette

settee

















 

zz









 

                   blizzard
                   buzzard
                   dizzy
                   fuzzy







 

hazard          present
hesitate        president
lizard            resident
lozenge         miserable
wizard            prison
wizened         risen
                     closet
closet           deposit
desert            positive
designate       visible
desolate          visit
hesitate          scissors

49 words have unpredictable final -ff, -ll and -ss