natatorium

noun, plural na·ta·to·ri·ums, na·ta·to·ri·a [ney-tuh–tawr-ee-uh, –tohr-, nat-uh-] /ˌneɪ təˈtɔr i ə, -ˈtoʊr-, ˌnæt ə-/.

1. a swimming pool, especially one that is indoors.

noun plural -riums or -ria (-rɪə)

1. rare a swimming pool, esp an indoor pool

n.1890, New Englandish word for “swimming pool,” from Latin natator “swimmer” (from nare “to swim”) + -ium, neuter suffix. Latin nare is from PIE root *sna- “to swim” (cf. Sanskrit snati “bathes;” Avestan snayeite “washes, cleans;” Armenian nay “wet, liquid,” Greek notios “wet, damp,” nekhein “to swim;” Middle Irish snaim “I swim,” snam “a swimming”). Middle English had natatorie “a pool, bath,” early 14c., from Latin.