The /ɑ/ vowel is usually spelled <ar> but we also find <a> in ta, <aa> in baa and the letter name R. The /əʊ/ diphthong is spelled <oCe>, <o>, <oa>, <oe>, <eau> in beau, and occurs in the letter name O.
This contrast is between a long vowel and a diphthong. The starting tongue positions are fairly close and confusions are possible, though not associated with any particular group of learners.
Interesting pairs include:
The density value is 4.85%. The pairs make 102 semantic contrasts, giving a loading of 50.7%.
Aachen oaken ah O aha oho alms ohms arc oak arcs oaks ardour odour ardours odours arm ohm arms ohms Art oat arts oats baa beau baas beaux baa bow baas bows baaing bowing baa'd bowed baa'd bode bar beau bars beaux bar bow bars bows barred bowed barred bode barman bowman barmen bowmen barn bone barns bones barter boater barters boaters behalves behoves blah blow cadre coda cadres codas calm comb calmed combed calming coaming calms combs calmer coma calmer comber Calne cone calve cove calves coves card code carded coded carding coding cards codes Carl coal carp cope carped coped carping coping carps copes cart coat carted coated carting coating carts coats cast coast casts coasts casting coasting caste coast castes coasts caster coaster casters coasters chars chose class close classes closes clerk cloak clerked cloaked clerking cloaking clerks cloaks crossbars crossbows darling doling dart dote darted doted darting doting darts dotes fa foe farm foam farmed foamed farming foaming farms foams foremast foremost ghastly ghostly grass gross grassed grossed grasses grosses grassing grossing grave grove graves groves Graz groats guard goad guarded goaded guarding goading guards goads ha ho halve Hove hard hoed harks hoax harm home harmed homed harming homing harmless homeless harms homes harp hope harped hoped harping hoping harps hopes karma coma karmas comas khan cone khans cones la lo lard load larded loaded larding loading larn loan larned loaned larning loaning larns loans lath loath laugh loaf laughed loafed laughing loafing laughs loafs ma Mo mar mow mars mows marred mowed marred mode mark moke marks mokes marl mole mart moat marts moats Martian motion Martians motions martyr motor martyred motored martyring motoring martyrs motors mast most parch poach parched poached parches poaches parching poaching park poke parked poked parking poking parks pokes parka poker parkas pokers parky poky parlour polar pars pose parrs pose parse pose parsed posed parses poses parsing posing passed post pastor poster pastors posters past post pasts posts postcard postcode postcards postcodes R O R's O's rah roe rah row scarp scope shah shew shahs shews shard shewed smart smote spark spoke sparks spokes sparred Spode star stow starred stowed stars stows stark stoke starkers stokers start stoat starts stoats starve stove starves stoves ta toe tar toe tars toes tar tow tars tows tarred towed tarred toad tardy toady tarn tone tarns tones tart tote tarted toted tarting toting tarts totes topmast topmost
Credit: John Higgins