Horizontal ledge forming the base of a window.

• Interior or exterior surface used as a shelf.

Horizontal member forming the bottom of a doorway.

• The threshold you step over.

Base plate of a wall or frame resting on a foundation.

• Horizontal member bearing the uprights.

Tabular igneous intrusion parallel to surrounding strata.

• A concordant sheet of cooled magma.

Threshold across a lock chamber floor against which gates close.

• Protects the gates’ bottoms and seals water.

Raised ridge at the base of the nasal aperture in the skull.

• Anatomical landmark in forensics and anthropology.