The /ɑ/ vowel is usually spelled <ar> but we also find <ear> in heart, <aa> in baas, <a> in lakh and the letter name R. The /ʌ/ vowel is normally spelled <u>, but is <ou> in couple or <oCe> in some.
This contrast is between a long and a short vowel which are close together in the mouth. It is a recognised problem for Spanish, Greek and Swahili speakers and probably for other learners too.
There are several pairs involving taboo words: balm/bum, bastard/bustard and can't/cunt.
Interesting pairs include:
calmly comely
carpal couple
martyr mutter
The density value is 4.27%. The pairs make 90 semantic contrasts, giving a loading of 50.8%.
baa'd bud baas bus baas buzz balm bum barbel bubble barbels bubbles barge budge barged budged barges budges barging budging bark buck barked bucked barking bucking barks bucks barn bun barter butter bartered buttered bartering buttering barters butters bastard bustard bastards bustards branch brunch branches brunches calf cuff calm come calmer comer calming coming calms comes calmly comely can't cunt card cud Carl cull carp cup carped cupped carping cupping carps cups carpal couple carpals couples cart cut carter cutter carters cutters carting cutting carts cuts carver cover carvers covers charm chum charmed chummed charming chumming charms chums clerk cluck clerked clucked clerking clucking clerks clucks karmas comers dance dunce dances dunces dark duck Darkey ducky Darkeys duckies darling dulling darn done darned dunned darning dunning darns duns dramas drummers farce fuss farces fusses Farsi fussy fart phut fast fussed garner gunner garners gunners garter gutter garters gutters grant grunt granted grunted granting grunting grants grunts graph gruff haft huffed half huff harm hum harmed hummed harming humming harms hums harsh hush hart hut harts huts heart hut hearts huts hearted hutted laager lugger laagers luggers lakh luck lakhs luxe Largs lugs last lust lasted lusted lasting lusting lasts lusts laugh luff laughed luffed laughing luffing laughs luffs mark muck marked mucked marking mucking marks mucks marl mull marred mud marsh mush marshier mushier marshiest mushiest marshy mushy mart mutt martyr mutter martyred muttered martyring muttering martyrs mutters mast mussed master muster mastering mustering masters musters mastered mustard masts musts park puck parks pucks parka pukka parkas puckers part putt parted putted parting putting parts putts party puttee parties puttees pass pus plaque pluck plaques plucks psalm some psalms sums R's us raft roughed sahib sub sahibs subs scarf scuff scarfs scuffs scarper scupper scarpered scuppered scarpering scuppering scarpers scuppers scarred scud shan't shunt shark shuck sharks shucks smart smut smarted smutted smarting smutting smarts smuts sparred spud staff stuff staffed stuffed staffing stuffing staffs stuffs stark stuck starred stud starter stutter starters stutters sari Surrey tarn ton tarns tons tarsal tussle tarsals tussles tart tut tarted tutted tarting tutting task tusk tasks tusks