==> language/english/spelling/operations.on.words/substitution.s <==
longest onalosi (substitution in every position possible) 
 PASTERS: MASTERS,POSTERS,PALTERS,PASSERS,PASTORS,PASTELS,PASTERN 	
shortest isolano (no substitution possible) 
 ECRU 
longest word, all letters changed to other letters in minimum number of
steps, yielding another word  THUMBING-THUMPING-TRUMPING-TRAMPING-
 TRAPPING-CRAPPING-CRAPPIES-CRAPPOES 
longest word girders  BADGER/SUNLIT, BUDLET/SANGIR (6)
longest word with full vowel substitution 
 CL(A,E,I,O,U)CKING (8) also Y D(A,E,I,O,U,Y)NE (4) 
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)
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Unless noted otherwise, all words occur in Webster's Third New International
Dictionary, Merriam-Webster, Springfield, MA, 1961.