socle

In architecture, a plain base that supports and elevates a column, statue, pedestal, wall, or other structure. While often used interchangeably with plinth, in English the term socle is used more specifically for smaller, less elaborate bases, while plinth is used for larger or more ornate supports. Pronunciation here.

Socle for the Column of Aelia Eudoxia. Istanbul, Türkiye. Marble. Early Byzantine. 403 CE.