The /f/ sound is spelled with <f>, <ff>, <gh> in cough or <ph> in phone. The /n/ sound is spelled <n>, <nn> or <kn> in known.
The contrast is between a voiceless labio-dental fricative and a voiced alveolar nasal continuant. It is not usually a problem.
Taboo word pairs include cuffed/cunt, fanny/nanny, and the very offensive figure/nigger.
Notice how the words fife and nine each pair off with fine and knife. Other interesting pairs include:
feather nether
foreman Norman
offer honour
ruffle runnel
The mean density value is 1.6%. The list makes 173 semantic distinctions, a loading of 60%.
afield annealed aft aren't beef bean beefs beans biff bin biffs bins bluffed blunt buff bun buffs buns caff can caffs cans calf Calne chafe chain chafing chaining chafes chains chafed cahined chaffed chant chaffs chance coffee Connie coif coign cough con coughing conning coughs cons coughed conned coughed cont cuffed cunt cuffing cunning deaf den deft dent defy deny defied denied defies denies defying denying differ dinner differs dinners doff don doffing donning doffs dons doffed donned F N fab nab fade neighed fag nag fagged nagged fagging nagging fags nags fail nail failed nailed failing nailing fails nails fair ne'er fame name famed named fancy Nancy fanny nanny fannies nannies fare ne'er farrow narrow farrowed narrowed farrowing narrowing farrows narrows fat gnat fats gnats fat Nat fatal natal fatter natter fatty natty fattier nattier fattiest nattiest faugh gnaw faugh nor fear near feared neared fearing nearing fears nears feather nether fed Ned fee knee fees knees feed knead feeding kneading feeds kneads fell nell felt knelt fester Nestor fetid netted fettle nettle feud nude feuds nudes few knew few new fewer newer fewest newest fewness newness fey née fib nib fibs nibs fickle nickel fie nigh fife fine fife knife fifes knifes fifty nifty fight knight fights knights fighting knighting fight night fights nights fighter nitre figure nigger figures niggers figured niggard fill nil fine nine fines nines fire nigher first nursed fit knit fits knits fitted knitted fitting knitting fitter knitter fitters knitters fives knives fix nicks foal knoll foals knolls foam gnome foams gnomes fob knob fobs knobs foe know foes knows foe no for gnaw for nor force Norse ford gnawed fore gnaw fore nor foreman Norman form norm forms norms formal normal formally normally formality normality formalize normalize formalized normalized formalizes normalizes formalizing normalizing formative normative forty naughty four gnaw fours gnaws four nor fox knocks fudge nudge fudges nudges fudged nudged fudges nudges fuel newel fuels newels fun none fun nun fury Newry fuse news Geoff gen goof goon goofs goons graft grant grafted granted grafting granting grafts grants grief green huff Hun huffed hunt huffy honey if in kaffir canna kaffirs cannas knife nine laugh Larne laughing larning laughs lance leaf lean leafing leaning left lent life line lifer liner lifers liners lift lint lifts Linz loaf loan loafing loaning loafs loans loafed loaned mid-off mid-on NAAFI nanny niffy ninny oaf own oafs owns off on offer honour offered honoured offering honouring offers honours off-licence on-licence off-licences on-licences offset onset offsets onsets phase neighs phone known phut nut proof prune proofing pruning proofs prunes proofed pruned puff pun puffing punning puffed punned puffs puns puffed punt quiff quin quiffs quince ref Rennes ref wren refs wrens reft rent refuse renews rife Rhine riffs rinse roof rune roofs runes rough run roughing running roughs runs roughed runt rougher runner ruffle runnel ruffles runnels safe sane safely sanely safer saner safest sanest scoff scone scoff scones scoffs sconce shaft shan't sheaf sheen skiff skin skiffs skins sphere sneer spheres sneers sough son soughs sons sough sun soughing sunning soughs suns soughed sunned spoof spoon spoofing spooning stuff stun stuffed stunned stuffing stunning stuffs stuns stuffed stunt tiff tin tough ton toughie tunny toughies tunnies turf tern turf turn turfing turning turfed turned turfs turns turn-off turn-on waft want wafted wanted wafting wanting wafts wants waif Wayne waif wane waifs wanes wharf warn weft went whiff whin whiff win whiffs wins whiffs wince wife whine
John Higgins, Shaftesbury, October 2010.