==> language/english/spelling/operations.on.words/insertion.s <==
   longest hydration (double reheadment)  (D,R)EVOLUTIONIST (12/13)
   longest hospitable word (insert letter anywhere) 
    CARES: SCARES, CHARES, CADRES, CARIES, CARETS, CARESS 
   shortest hostile word (no deletion possible)  SYZYGY (6)
****
Unless noted otherwise, all words occur in Webster's Third New International
Dictionary, Merriam-Webster, Springfield, MA, 1961.