Q: What exceptional words turn into other words by substitution of letters?
A: longest onalosi (substitution in every position possible)
BANDIES:CANDIES->BUNDIES->BADDIES->BANGIES->BANDSES->BANDITS->BANDIED (7) BROWSES:CROWSES->BLOWSES->BREWSES->BROOSES->BROWZES->BROWSTS->BROWSED (7) CARACAS:MARACAS->CURACAS->CAMACAS->CARICAS->CARANAS->CARACKS->CARACAL (7) CLASSES:GLASSES->CHASSES->CLESSES->CLADSES->CLASHES->CLASSIS->CLASSED (7) COLLIES:BOLLIES->CALLIES->COALIES->COLBIES->COLLSES->COLLINS->COLLIED (7) PASTERS:BASTERS->PESTERS->PALTERS->PASSERS->PASTORS->PASTELS->PASTERN (7)
shortest isolano (no substitution possible)
EPI (3)
longest word, all letters changed to other letters in minimum number of steps, yielding another word THUMBING-THUMPING-TRUMPING-TRAMPING-
TRAPPING-CRAPPING-CRAPPINS-CRAPPIES-CRAPPOES (8)
longest word girders BADGER/SUNLIT, BUDLET/SANGIR (6) longest word with full vowel substitution
BATTINGS->BETTINGS->BITTINGS->BOTTINGS->BUTTINGS (8) CLACKING->CLECKING->CLICKING->CLOCKING->CLUCKING (8) RACKLING->RECKLING->RICKLING->ROCKLING->RUCKLING (8) and Y
CATES->CETES->CITES->COTES->CUTES->CYTES (5) DANES->DENES->DINES->DONES->DUNES->DYNES (5) MARAS->MARES->MARIS->MAROS->MARUS->MARYS (5)
longest words with vowel substitutions
DESTRUCTIBILITIES, DISTRACTIBILITIES (17)
longest word constant-letter-shifted to another PRIMERO-SULPHUR (7)
arithmetical-letter-shifted DREAM-ETHER (5) constant-shift-with-transposal (shiftgrams) AEROPHANE-SILVERITE (9)
longest word pair shifted one position on typewriter keyboard WAXIER-ESCORT (6) longest word pair confusable on a telephone keypad AMOUNTS-CONTOUR (7) **** Unless noted otherwise, all words occur in Webster's Third New International Dictionary, Merriam-Webster, Springfield, MA, 1961.