Meaning of transition area

transi'tion ar"ea

Pronunciation: [key]
— Ling. Ling.
  1. (in dialect geography) an area whose dialect has been influenced by the dialect of one or more neighboring focal areas. Cf. focal area, relic area. Also called graded area.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.