The /f/ sound is spelled with <f>, <ff> or <ph> as in phase. The /r/ sound is spelled <r>, <rr> or <wr> in wrist. Notice how the homograph read makes pairs with feed and fed.
The contrast is between a voiceless labio-dental fricative and a voiced alveolar continuant. It is not a problem.
Taboo word pairs include fuck/ruck.
This pair occurs in the now common phrase "fun run". Other interesting pairs include:
fashion ration
fecund reckoned
morphine Maureen
wasteful wastrel
The mean density value is 1.7%. The list makes 125 semantic distinctions, a loading of 48%.
affable arable awful aural buffer borough buffers boroughs chaffing charring cheerfully cheerily coffee corrie coffees corries defect direct defected directed defecting directing defects directs defection direction defections directions defective directive defector director defectors directors defied deride effect erect effected erected effecting erecting effects erects enfold enrolled fa rah face race faced raced faces races facing racing facer racer facial racial fact racked fade raid faded raided fading raiding fades raids fag rag fagged ragged fagging ragging fags rags fail rail failed railed failing railing failings railings fails rails fain rain fain geign fain rein fair rare fairer rarer fairest rarest fairly rarely fake rake faked raked fakes rakes faking raking fancied rancid fanned rand far rah fare rare faring raring fascist rashest fashion ration fashioned rationed fashioning rationing fashions rations fat rat fatting ratting fatted ratted fats rats fate rate fates rates fated rated father rather fatter ratter fatty ratty fattier rattier fattiest rattiest faugh raw faugh roar favour raver favours ravers fear rear feared reared fearing rearing fears rears fearful feral fecund reckoned fee re feed read fed read feeding reading feeds reads feeder reader feeders readers feign rain feigned rained feigning raining feigns rains feign reign feigned reigned feigning reigning feigns reigns feign rein feigned reined feigning reining feigns reins fen Rennes fen wren fens wrens fend rend fending rending fends rends fender render fenders renders feoff reef feoffs reefs festive restive fetch retch fetched retched fetches retches fetching retching fête rate fêted rated fêting rating fêtes rates fetid retted fey ray fez res fib rib fibbed ribbed fibbing ribbing fibs ribs fiddle riddle fiddled riddled fiddles riddles fiddling riddling fie rye fife rife fig rig figs rigs fight right fighting righting fights rights fight rite fights rites fight write fighting writing fights writes fighter writer fighters writers figure rigger figures riggers file rile filed riled files riles filing riling final rhinal find rind finds rinds fine Rhine fire wrier fist wrist fists wrists five rive fives rives fluffy flurry foal rôle foals rôles foal roll foals rolls foaled rolled foaling rolling foam roam foams roams foamed roamed foaming roaming foam Rome fob rob fobbed robbed fobbing robbing fobs robs foe roe foes roes foe row foes rows foes rose fondle rondel fondles rondels food rood foods roods fool rule fooled ruled fooling ruling fools rules footle rootle footled rootled footles rootles footling rootling for raw for roar ford roared fore raw fore roar fort wrought foster roster fosters rosters fought wrought found round founded rounded founding rounding founds rounds founder rounder founders rounders four raw four roar fours roars Fowey Roy fox rocks fuck ruck fucked rucked fucking rucking fucks rucks fuddle ruddle fuddled ruddled fuddles ruddles fuddling ruddling fug rug fugs rugs fumble rumble fumbled rumbled fumbles rumbles fumbling rumbling fun run funnel runnel funnels runnels funny runny funnier runnier funniest runniest fusty rusty huffy hurry morphine Maureen offertory oratory offertories oratories phase raise phased raised phases raises phasing raising phase rays Phil Rhyl phone roan phones roans phut rut staffing starring Taffy tarry Taffies tarries unfed unread unfold unrolled wasteful wastrel well-founded well-rounded