The /s/ sound is spelled with <s> or <c>. The /w/ sound is spelled with <w>.
This is a contrast between a voiceless sibilant fricative and a voiced bilabial semivowel, and can only occur initially or medially. It does not cause problems.
The only taboo word pair is sank/wamk.
Interesting pairs include:
ceiling wheeling
lapsing lapwing
saviour wavier
sorrier warrior
The mean density value is %. The list makes semantic distinctions, a loading of %.
assay away C we C wee C's wees cede weed ceded weeded ceding weeding cedes weeds ceiling wheeling cell well cells wells cent went cert wert cider wider cinch winch cite Wight cite white cites whites citing whiting city witty cyst whist lapsing lapwing leeway lycée psalter Walter sack whack sacked whacked sacking whacking sacks whacks sacks wax safe waif safes waifs safer wafer sag wag sagged wagged sagging wagging sags wags sage wage sages wages said wed sail wail sailed wailed sailing wailing sails wails sails Wales sail whale sails whales sailor whaler sailors whalers sake wake sakes wakes sale wail sales wails sales Wales sale whale sales whales sane wain sane wane sane Wayne sang whang sank wank sate wait sated waited sates waits sating waiting sate weight sates weights sating weighting sated weighted save waive saved waived saves waives saving waiving save wave saved waved saves waves saving waving saver waiver savers waivers saver waver savers wavers saviour wavier savour waver savoured wavered savouring wavering savours wavers savour waiver savours waivers saw war saws wars sawed warred sawhorse warhorse sawhorses warhorses sawn warn saxes waxes say way say weigh saying weighing scent went sea wee seas wees seal wheel seal wheels sealing wheeling sealed wheeled sealed weald sealed wield Sean shorn sear Wear seared weird sears weirs sedge wedge sedges wedges see wee seeing weeing sees wees seed weed seeded weeded seeding weeding seeds weeds seedy weedy seedier weedier seediest weediest seedling wheedling seek weak seek week seeks weeks seeker weaker seine wain seines wains seine wane seined waned seines wanes seining waning seine Wayne seize wees seize wheeze seized wheezed seizes wheezes seizing wheezing sell well sells wells selling welling send wend sending wending sent went sends wends sends wens senior weenier sense whence Sept wept set wet sets wets setting wetting settings wettings setter wetter sew woe sews woes sew whoa side wide sides wides sigh why sigh Y sighs Y's sighs wise sight white sights whites sighting whiting sight Wight sign whine signed whined signing whining signs whines Sikh weak Sikh week Sikhs weeks silly willy sillies willies silt wilt silted wilted silting wilting silts wilts simper whimper simpered whimpered simpering whimpering simpers whimpers simple wimple simples wimples since wince sink wink sinking winking sinks winks sip whip sipped whipped sips whips sipping whipping sir were sir whirr sirs whirrs sire wire sired wired sires wires siring wiring sit whit sit wit sits wits site white sites whites site Wight siting whiting size Y's size wise so woe so whoa soak woke soar war soaring warring soars wars soared warred soared ward sod wad sodded wadded sodding wadding sods wads soft waft sold wold son one sons ones son won sop whop sopped whopped sopping whopping sops whops sore war sores wars sorely Warley sorrier warrior sort wart sorts warts sorter water sorters waters sot watt sots watts sou woo sous woos sought wart sound wound sow woe sows woes sow whoa sow wow sowed wowed sows wows sowed woad sun one suns ones sun won sunder wonder sundered wondered sundering wondering sunders wonders surd whirred Surrey worry Susie woozy sword ward swords wards sylph Wilf unsound unwound
John Higgins, Shaftesbury, November 2010.