The /ɑ/ vowel is usually spelled <ar> but we also find <ear> in heart, <aa> in baa, <a> in lakh and the letter name R. The /3/ vowel is spelled <er>, <ir>, <ur> or <ear>. In this dictionary it is also given as the pronunciation of the exclamation Ugh!, but that could be disputed.
This contrast is between two long vowels which are fairly close together in the mouth. It is potential source of confusion, though not associated with particular group of learners.
The only pair involving taboo words is arse/erse.
Interesting pairs include:
The density value is 5.06%. The pairs make 80 semantic contrasts, giving a loading of 51.3%.
ah ugh arc irk arcs irks ark irk arks irks argent urgent argot ergo arse Erse baa burr baas burrs baa'd bird bar burr bars burrs barbel burble barbels burbles bark burke barked burked barking burking barks burkes barley burly barn burn barns burns Bart Bert bath berth bathed berthed bathing berthing baths berths bath birth baths births barn Berne barn burn barns burns Cali curly calve curve calved curved calves curves calving curving car cur cars curs card curd cards curds Carl curl carnal Colonel cart curt carton curtain cartons curtains cast cursed Charles churls dark dirk dart dirt darted dirtied derby derby derbies derbies far fir far fur farm firm farmed firmed farming firming farms firms farmer firmer farthest furthest fast first fasts firsts father further fathered furthered fathering furthering fathers furthers gargle gurgle gargled gurgled gargles gurgles gargling gurgling guard gird guarded girded guarding girding guards girds hard heard hart hurt harts hurts harts Hertz heart hurt hearts hurts hearts hertz lakh lurk lakhs lurks lark lurk larked lurked larking lurking larks lurks larch lurch larches lurches larn learn larned learned larning learning larns learns Mach murk mark murk mar myrrh Marge merge palm perm palmed permed palming perming palms perms pa per par per parr per pa purr pas purrs par purr pars purrs parr purr parrs purrs parch perch parched perched parches perches parching perching park perk parked perked parking perking parks perks parky perky parley pearly parson person parsons persons parsonage personage parsonages personages part pert partly pertly pass purse passed pursed passes purses passing pursing pasha Persia quark quirk quarks quirks R err R's errs scarf scurf shark shirk sharks shirks spar spur sparred spurred sparring spurring spars spurs star stir starred stirred starring stirring stars stirs starling Stirling suave swerve tarn tern tarns terns vast versed yarn yearn yarned yearned yarning yearning yarns yearns
Credit: John Higgins