capstone

/K AE1 P S T OW0 N/
noun
  1. 1

    Any of the stones making up the top layer of a wall; a coping stone.

  2. 2

    A crowning achievement, culmination or finishing touch.

Synonyms

verb
  1. 1

    To complete as a crowning achievement; to top off.

  2. 2

    To train in the Capstone Military Leadership Program.

Source: https://en.wiktionary.org/wiki/capstone