Which structure is characterized by a warm-water chamber typically found in Roman baths?

The tepidarium is specifically designed as a warm-water chamber within Roman baths, serving the function of transitioning bathers from the cold to hot baths. Its name, derived from the Latin "tepidus," meaning "warm," reflects its temperature. The tepidarium typically features heated walls, contributing to a comfortable environment for relaxation and preparation for the more intense heat of the caldarium, the hot bath section.

In contrast to the tepidarium, the taberna refers to shops or spaces in a Roman building, not associated with bathing. The spandrel generally relates to architectural design, indicating the space between the top of an arch and the ceiling or wall above it, without any connection to baths. Lastly, pseudoperipteral describes a building that mimics the appearance of a peripteral structure (one surrounded by columns) but lacks true columns, which is unrelated to bathing facilities. Therefore, the tepidarium stands out as the correct choice, specifically fulfilling a role in the thermal experience of Roman bath culture.