The /3/ vowel is spelled with <er>, <ir>, <ear>, <ur>, and <or> in work. The /əʊ/ diphthong is spelled <oCe>, or <oa>, <ow>, and appears in the letter name O.
This is a contrast between a long vowel and a diphthong. The starting positions are very close, and it can be a problem particularly for learners who try too hard to imitate an RP /əʊ/, notably Scandinavians.
Interesting pairs include:
earldom Oldham
fermentation fomentation
immersion emotion
The density figure is 5.81%. The set makes 88 semantic contrasts giving a loading of 49.2%.
Bernie bony bestir bestow bestirred bestowed bestirs bestows bird bode birds bodes blur blow blurred blowed blurs blows blurt bloat blurted bloated blurting bloating blurts bloats burn bone burned boned burning boning burns bones burner boner burners boners burr bow burrs bows burr beau burrs beaux burst boast bursting boasting bursts boasts curd code curds codes curl coal curling coaling curls coals curled coaled curler cola curlers colas cursed coast curt coat curve cove curves coves dirge doge dirges doges dirt dote dirtied doted dirty dhoti dirties dhotis durst dosed earldom Oldham earn own earned owned earning owning earns owns err O errs O's erred ode erred owed fermentation fomentation fern phone ferns phones ferny phoney firm foam firmed foamed firming foaming firms foams fir foe firs foes flirt float flirted floated flirting floating flirts floats flirtation floatation flirtations floatations fur foe furs foes furl foal furled foaled furling foaling furls foals gird goad girded goaded girding goading girds goads girl goal girls goals heard hoed Herne hone her hoe hers hoes hurl hole hurled hold hurling holing hurls holes immersion emotion immersions emotions incurred encode intern intone interned intoned interning intoning interns intones irk oak irks oaks jerk joke jerked joked jerking joking jerks jokes journey Joanie kirk coke kirks cokes Kirkby Kobe kirks coax learn loan learned loaned learning loaning learns loans learn lone murk moke pearl pole pearls poles pearl poll pearled polled pearling polling pearls polls perch poach perched poached perches poaches perching poaching perk poke perked poked perking poking perks pokes perky poky perkier pokier perkiest pokiest purrs pose pursed post sir sew sirs sews sir so sir sow sirs sows slur slow slurred slowed slurs sloes smirk smoke smirked smoked smirking smoking smirks smokes spurred Spode stern stone sterns stones stir stow stirred stowed stirs stows surd sowed surly solely tern tone terns tones tourney Tony turd toad turds toads Turk toque Turks toques turn tone turned toned turning toning turns tones turps topes turtle total turtles totals ugh O unfurled unfold urban Oban were woe weren't won't whirled wold whirr woe whirrs woes whirred woad work woke world wold worlds wolds
Credit: John Higgins