boundary vs tail end

boundary

noun
  • The bounds, confines, or limits between immaterial things (such as one’s comfort zone, privacy, or professional sphere and the realm beyond). 

  • An edge or line marking an edge of the playing field. 

  • The dividing line or location between two areas. 

  • An event whereby the ball is struck and either touches or passes over a boundary (with or without bouncing), usually resulting in an award of 4 (four) or 6 (six) runs respectively for the batting team. 

  • (of a set) The set of points in the closure of a set S, not belonging to the interior of that set. 

tail end

noun
  • The hindmost part of anything (a person, animal, or object), the rear end; the butt, buttocks; hindquarters, rump. 

  • The last part of a period of time, event, or situation; the concluding or final part. 

How often have the words boundary and tail end occurred in a corpus of books? (source: Google Ngram Viewer )