keystone

the central stone in an arch that locks all the other stones into position and supports the whole structure

piedra clave, piedra angular

Collocations keystone of a building

• The keystone is the most important part of the arch.

  La piedra clave es la parte más importante del arco.

an idea, principle, or person that is central to a system and holds all the other parts together

piedra angular, elemento clave

Collocations keystone of an argument

• The concept of democracy is the keystone of Western political thought.

  El concepto de la democracia es el elemento clave del pensamiento político occidental.