- North American
a swimming pool, especially one that is indoors.
A natatorium (plural: natatoria) is a building containing a swimming pool. In Latin, a cella natatoria was a swimming pool in its own building, although it is sometimes also used to refer to any indoor pool even if not housed in a dedicated building (e.g., a pool in a school or a fitness club).— wiki/Natatorium
Origin: late 19th cent.: from late Latin, neuter (used as a noun) of natatorius ‘relating to a swimmer,’ from natare ‘to swim.’
natatoriums (plural noun)