A recess in a wall, often designed to contain and frame a statue, relief, shrine, or other sculptural element.
A niche is a recess formed in a wall. In architecture, niches are frequently designed to contain sculpture, including standing figures, busts, devotional images, funerary monuments, fountains, and ornamental carving.
The niche creates both a physical setting and a compositional frame. Its height, depth, curvature, base, canopy, and lighting can strongly influence the pose, projection, silhouette, viewing angle, and scale of the sculpture placed within it.
Etymology
From French niche, referring to a recess or sheltered space.
Sculptor Notes
A figure designed for a niche should be conceived for the niche from the beginning. Deep recesses suppress lateral views and light; shallow niches demand a stronger silhouette. The architecture therefore becomes part of the sculpture's composition rather than a neutral container.
References
https://www.getty.edu/vow/AATFullDisplay?subjectid=300002704