The spelling of /p/ is always either <p> or <pp>. There is a range of spellings for the /f/ sound including <f>, <ff>, <gh> in sough or <ph> in sphere.
Although /p/ is a stop and /f/ a fricative, the articulations are close enough to present a problem for some learners, especially when the sounds occur in clusters. It is a known problem for Arabic speakers.
There are a number of rude word confusions in this set: pee/fee, pissed/fist, puck/fuck, and pucker/fucker.
Interesting pairs include
The mean density value is 4.9%. The list makes 310 semantic distinctions, a loading of 54%.
alp Alf appealed afield append offend appended offended appending offending appends offends appraise affrays beep beef beeps beefs camper camphor cap caff caps caffs carp calf cheap chief cheaply chiefly cheep chief cheeps chiefs clip cliff clips cliffs cop cough copped coughed copping coughing cops coughs copper coffer coppers coffers copse coughs Copt coughed copy coffee copies coffees creep Crieff cropped croft cup cuff cupped cuffed cupping cuffing cups cuffs dep deaf depend defend depended defended depending defending depends defends dependant defendant dependants defendants dipper differ dippers differs dripped drift Epping effing gap gaff gaps gaffs gap gaffe gaps gaffes grippe grief grippes griefs gulp gulf gulps gulfs harp half harped haft hoop hoof hoops hoofs kopje coffee kopjes coffees leap leaf leaped leafed leaping leafing leaps leafs leap lief leapt left limp lymph lipped lift lope loaf loped loafed lopes loafs loping loafing lopped loft nappy NAAFI nip niff nips niffs nippy niffy nippier niffier nippiest niffiest op off opp off opt oft outport outfought overleap overleaf P fee P's fees pa fa pa far pace face paced faced paces faces pacing facing packed fact pact fact pacts facts pad fad pads fads paddy faddy pah fa pah far paid fade pail fail pails fails pain fain pain feign pained feigned paining feigning pains feigns paint faint painted fainted painting fainting paints faints paint feint painted feinted painting feinting paints feints painter fainter pair fair pairs fairs pair fare paired fared pairing faring pairs fares pale fail paled failed pales fails paling failing palings failings pall fall palling falling palls falls palm farm palmed farmed palming farming palms farms palmer farmer palmers farmers palter falter paltered faltered paltering faltering palters falters pan fan panned fanned panning fanning pans fans pane fain pane feign panes feigns pang fang pangs fangs par fa par far pare fair pares fairs pare fare pared fared pares fares paring faring Parma farmer parr fa parr far parson fasten parsons fastens part fart parted farted parting farting parts farts pass farce passes farces passed fast passion fashion passions fashions past fast pasts fasts paste faced pastor faster pat fat pats fats patted fatted patting fatting pate f^ete pates f^etes pate fate pates fates patten fatten pattens fattens patter fatter pattern fatten patterned fattened patterning fattening patterns fattens patty fatty Paul fall pause fours paw faugh paw for paw fore paw four paws fours pawed ford pawl fall pawls falls pawn faun pawns fauns pawn fawn pawned fawned pawning fawning pawns fawns pay fey pays phase pea fee peas fees peal feel pealing feeling peals feels pealed field pear fair pears fairs pear fare pears fares pearl furl pearled furled pearling furling pearls furls peasant pheasant peasants pheasants pease fees peat feat peat feet pee fee peeing feeing pees fees peed feed peel feel peels feels peeled field peeler feeler peelers feelers peeling feeling peelings feelings peer fear peered feared peering fearing peers fears peerless fearless pelt felt pen fen pens fens pence fence pending fending penned fend per fir per fur perm firm permed firmed perming firming perms firms perry ferry Perth firth pester fester pestered festered pestering festering pesters festers petal fettle Pete feat Pete feet petted fetid pettish fetish pew few pew phew pews fuse pi fie pickle fickle picks fix piddle fiddle piddled fiddled piddles fiddles piddling fiddling pie fie pieced feast pier fear piers fears pierce fierce pig fig pigs figs pigment figment pigments figments pile file piled filed piles files piling filing pill fill pills fills pill Phil pin fin pins fins pin Finn pins Finns pinch finch pinches finches pine fine pined fined pines fines pining fining pined find pinnace finis pipe fife pipes fifes pissed fist pit fit pits fits pitted fitted pitting fitting pitied fitted pixies fixes plait flat plaits flats plan flan plans flans plank flank planked flanked planking flanking planks flanks plash flash plashed flashed plashes flashes plashing flashing platter flatter platters flatters play flay played flayed playing flaying plays flays plea flea pleas fleas plea flee pleas flees please fleas please flees pleat fleet pleating fleeting pleats fleets pled fled pledged fledged pliers fliers plight flight plighted flighted plighting flighting plights flights plop flop plopped flopped plopping flopping plops flops plucks flux plume flume plumes flumes plunk flunk plunks flunks plush flush ply fly plies flies plying flying pocks fox podgier Foggia poke folk pokes folks pole foal poles foals polio folio poll foal polled foaled polling foaling polls foals polled fold Polly folly poly folly polys follies pond fond ponder fonder pone phone pones phones pony phoney ponies phoneys pool fool pooled fooled pooling fooling pools fools poop pouffe poops pouffes pop fop pops fops pore faugh pore for pore fore pore four pores fours pored ford pork fork porn faun porn fawn porridge forage port fort ports forts port fought pose foes posses fosses pound found pounded founded pounding founding pounds founds pounder founder pounders founders pour faugh pour for pour fore pour four pours fours poured ford pox fox praise frays praise phrase praised phrased praises phrases praising phrasing prance France prank franc pranks francs prank frank pranks franks prate freight prated freighted prates freights prating freighting pray fray prayed frayed praying fraying prays frays prays phrase pressure fresher pressures freshers prey fray preyed frayed preying fraying preys frays preys phrase pride fried prior friar priors friars prior fryer priors fryers prise fries prize fries pro fro prom from prop Prof proper proffer propound profound pros froze prose froze prow Frau prox frocks pry fry pried fried pries fries prying frying puck fuck pucker fucker puckers fuckers pucks fucks puddle fuddle puddled fuddled puddles fuddles puddling fuddling pug fug pugs fugs pukka fucker pull full pulley fully pun fun punk funk punks funks punned fund pup puff pups puffs puppy puffy purer fuehrer purl furl purled furled purling furling purls furls purr fir purrs firs purr fur purrs furs purrs furze pursed first pus fuss put foot puts foots putt phut pyre fire pyres fires pyx fix pyxes fixes quip quiff quips quiffs reap reef reaped reefed reaper reefer reapers reefers reaping reefing reaps reefs repine refine repined refined repines refines repining refining repp ref reputation refutation reputations refutations repute refute reputed refuted reputes refutes reputing refuting rip riff rips riffs ripe rife ripped rift ripple riffle rippled riffled ripples riffles rippling riffling scarp scarf scarps scarfs sheep sheaf shipped shift sipped sift skip skiff skips skiffs snip sniff snipped sniffed snipping sniffing snips sniffs soapier Sofia soapy Sophie sopped soft spear sphere spears spheres stripe strife sup sough supped soughed supping soughing sups soughs supper suffer suppers suffers tip tiff tips tiffs top toff tops toffs tup tough tups toughs turps turfs warp wharf warps wharfs wept weft whip whiff whips whiffs whoop hoof whoops hoofs whopped waft wipe wife
John Higgins, Shaftesbury, January 2010.