Two collections of words.
For Kickshaws, Jeremy Morse sent "two collections of dictionary words (lowercase, unhyphenated), each of which has one weak link which your readers may be able to repair."
1. On the analogy of the well-known type-collection of AEIOU words, here is a collection of ABCD words from Chambers and OED unabridged dictionaries.
ABCD ABSCOND ABDC ABDUCT ACBD ASCRIBED ACDB ASCENDIBLE ADBC ROADBLOCK ADCB TRADUCIBLE BACD BACKED BADC BARDIC BCAB BROCADE BCDA HERBICIDAL BDAC BIRDWATCHER BDCA BIRDCAGE CABD CARBIDE CADB CANDLEBERRY CBAD CUPBOARD CBDA CUBOIDAL CDAB CREDITABLE CDBA CUDBEAR DABC DIABETIC DACB DANCEABLE DBAC DEBAUCH DBCA DISBOSCATION DCAB EDUCABLE DCBA DECUBITAL
2. And here is a collection of words showing a high degree of invariance with the months of the year and days of the week.
JAGUARS, TEXTUARY, LARCH, APRON, BAY, TUNE, DULY, AUGURY, SEPTENARY, OCTOPUS, REMEMBER, REMEMBER.
SUNDAE, MONKEY, OUTSTAY, YESTERDAY, THUNDER, FRIAR, SATURATE.
ANSWERS AND SOLUTIONS
1. The weak link is DANCEABLE with its second A.
2. The weak link here is THURSDAY/THUNDERY with only 50% invariable. Other matching patterns are THURIBLE, THIRSTED, TOURISTY, TORRIDLY, TEAR AWAY, CHURCHLY, OVERSTAY, EVERYDAY, DOOMSDAY.