What term is loosely applied to fish ponds and swimming pools, regardless of heating?

The term "piscina" is specifically used to refer to fish ponds and, by extension, swimming pools, regardless of whether they are heated or not. In ancient Roman contexts, a piscina could denote a body of water often utilized for fish farming or as a decorative water feature in villas and gardens. The usage of this term reflects not only the physical structure but also its role in the aquatic lifestyle and leisure activities of the time.

In contrast, a nymphaeum typically refers to a monument consecrated to the nymphs, often featuring a fountain or water source and is more focused on a shrine-type context rather than the functional aspects of recreation or fish farming. An hortus generally means "garden," which denotes more of a cultivated area rather than a water feature. A taberna refers to a shop or a workshop in Roman times, which does not relate to bodies of water at all. This background illustrates why "piscina" is the most appropriate term in this context as it aligns directly with the idea of fish ponds and swimming pools.