sill

This term describes the structural base of an opening, evoking a sense of boundary and transition. It is most commonly associated with the domestic comfort of a window, where it serves as a resting place for objects like plants or ornaments. In the context of a doorway, the word overlaps with the concept of a threshold, marking the physical and symbolic point of entry into a space. It implies a hard, flat surface designed to support the frame and repel water from the building's interior.