The /k/ sound is spelled with <c> or <k> initially, and <ck> or <ke> medially or finally, but note the unusal <qu> in quay. The /ʃ/ sound is normally spelled <sh>, and sometimes <ch> especially in words of French origin such as champagne or cloche.
The contrast is between a velar stop and an alveolar fricative, both voiceless. It causes no problems.
Interesting pairs include:
broker brochure
callow shallow
campaign champagne
caucus cautious
colder shoulder
coward showered
speckle special
Taboo word pairs include: cunt/shunt and kit/shit.
The mean density value is 1.7%. The list makes 129 semantic distinctions, a loading of 56%.
aback abash back bash backed bashed backing bashing balk borsch book bush booked bushed bookie bushy bookies bushes broker brochure brokers brochures cabby shabby cackle shackle cackled shackled cackles shackles cackling shackling cad shad cake shake cakes shakes caking shaking call shawl calls shawls callow shallow cam sham cams shams came shame campaign champagne campaigns champagnes candy shandy candies shandies can't shan't cape shape capes shapes card shard cards shards care share cared shared cares shares caring sharing carp sharp carps sharps Carron Sharon car shah cars shahs cat shat caucus cautious caught short cause shores cave shave caved shaved caves shaves caving shaving caw Shaw caw shore cawed shored caws shores checker Cheshire clack clash clacked clashed clacking clashing clock cloche Co show coal shoal coaled shoaled coaling shoaling coals shoals cock cosh cocked coshed cocking coshing cock shock cocking shocking cocks shocks cocked shocked cocker shocker cockers shockers cod shod code showed colder shoulder con shone cone shown coo shoe cooing shoeing coos shoes cook shook cookie cushy coot chute coots chutes coot shoot coots shoots cop shop copping shopping cops shops copped shopped copper shopper coppers shoppers Copt shopped core Shaw core shore cores shores coring shoring corn Sean corn shorn cot shot cots shots cotton Shotton could should couldn't shouldn't court short courted shorted courting shorting courts shorts courtly shortly coward showered cower shower cowering showering cowers showers cowered showered crack crash cracked crashed cracking crashing crake crêche crank shrank crew shrew crews shrews crewed shrewd crimp shrimp crimped shrimped crimping shrimping crimps shrimps croquet crochet crowd shroud crowded shrouded crowding shrouding crowds shrouds crude shrewd crudely shrewdly cruder shrewder crudest shrewdest cunning shunning cunt shunt cunts shunts curly Shirley curt shirt cut shut cuts shuts cutting shutting cutter shutter cutters shutters Dick dish dickeys dishes Dicky dishy flak flash fleck flesh hack hash hacked hashed hacking hashing hark harsh kail shale Kerry sherry key she keys she's killing shilling killings shillings kine shine kip ship kipped shipped kipping shipping kips ships kipper shipper kippers shippers kirk shirk kirks shirks kissed schist kit shit kitted shitted knack gnash knock nosh knocked noshed knocking noshing K's chaise lack lash lacked lashed lacking lashing lackeys lashes leak leash leek leash luck lush mac mash mark marsh muck mush mucky mushy muckier mushier muckiest mushiest parka pasha parkas pashas pluck plush plucky plushy pluckier plushier pluckiest plushiest pock posh pocked poshed public publish quay she rack rash relic relish relict relished ruck rush rucked rushed rucking rushing sack sash shook shush slack slash slacked slashed slacking slashing smack smash smacked smashed smacking smashing smacker smasher smackers smashers speckle special speckles specials stack stash stacked stashed stacking stashing track trash tracked trashed tracking trashing whelk Welsh wick wish wrack rash