foundation

Concise Oxford English Dictionary © 2008 Oxford University Press:
foundation/faʊnˈdeɪʃn/

▶noun

• 1 the lowest load-bearing part of a building, typically below ground level.

• 2 an underlying basis or principle.

  ■ [often with neg.] justification or reason.

• 3 the action of founding an institution or organization.

  ■ an institution established with an endowment.

• 4 a cream or powder applied to the face as a base for other make-up.

– derivatives
foundational adjective.