The /ɑ/ vowel is usually spelled <ar> but we also find <a> in pa and <aa> in kraal, along with the letter name R. The /ɔ/ vowel has a number of spellings including <or> in order, <oar> in board, <our> in course, <au> in author and <aw> in dawn.
This contrast is between two long vowels whose tongue positions are fairly close but which are also distinguished by lip-rounding. Confusions are possible, and this is a known problem for Dutch learners among others.
There is one set of pairs involving a taboo word: fart/fort.
Interesting pairs include:
The density value is 5.29%. The pairs make 130 semantic contrasts, giving a loading of 59.4%.
afar afore ah awe ah or ah ore arc auk arcs auks ardour order ardours orders art aught Arthur author artistic autistic baa'd bawd baa'd board baa'd bored baas boars balk bark balked barked balks barks bar boar bars boars bar bore barred bored barring boring bars bores barbel bauble barbels baubles bard bawd bards bawds bard board bards boards bard bored Barking balking barn Bourne barred bawd barred board barred bored calm corm calms corms Calne corn car caw cars caws car core cars cores cars cause carcase caucus carcases caucuses card cawed card chord cards chords card cord cards cords carded corded carding cording Carl call carp Corp carps corpse cart caught cart court carted courted carting courting carts courts cast coursed char chaw chars chaws char chore chars chores Chard chawed Charlie Chorley compartment comportment compartments comportments darn dawn darned dawned darning dawning darns dawns depart deport departed deported departing deporting department deportment departs deports discard discord discards discords fa faugh far faugh far for far fore farce force farces forces farm form farmed formed farming forming farms forms farmer former fart fort farts forts fast forced garden Gordon guard gaud guards gauds guardian Gordian ha haw hard hawed hard hoard hard horde harder hoarder hark hawk harked hawked harking hawking harks hawks harm haulm hearten Houghton hearty haughty heartier haughtier heartiest haughtiest heartily haughtily impart import imparted imported imparting importing imparts imports jar jaw jarred jawed jars jaws khan corn khans corns kraal crawl kraals crawls la law lard laud larded lauded larding lauding lards lauds larn lawn larns lawns ma maw Mali Morley mar maw mars maws mar more marl maul marred Maud Mars maws martyr mortar martyred mortared martyring mortaring martyrs mortars pa paw pa pore pa pour par paw pars paws par pore pars pores parred pored parring poring par pour pars pours parred poured parring pouring pars pause parr paw parrs paws parr pore parrs pores parr pour parrs pours parrs pause parch porch parches porches park pork parka porker parkas porkers parky pawky parse pause parsed paused parses pauses parsing pausing parse paws parse pores parse pours part port parted ported parting porting parts ports partly portly R awe R or R ore R's ores rah raw R's awes sake Sauchie scar score scarred scored scarring scoring scars scores shah shore shahs shores shard shored spar spore spars spores stark stalk starker stalker starkers stalkers starling stalling star store starred stored starring storing stars stores starry storey starry story tar tor tars tors tars tawse tarn torn tarry Tory tart taut tartly tautly tartness tautness tart taught tartar tauter yah yaw yard yawed yarn yawn yarned yawned yarning yawning yarns yawns
John Higgins, Shaftesbury, November 2009