aquarium:  Aquarium is a modern adaptation of the neuter form of the Latin adjective aquārius ‘watery’ (a noun aquārium existed in Roman times, but it meant ‘place where cattle drink’). Its model was vivarium, a 16th-century word for a ‘place for keeping live animals’. This was the term first pressed into service to describe such a place used for displaying fish and other aquatic life: in 1853 the magazine Athenaeum reported that ‘the new Fish house at the London Zoo has received the somewhat curious title of the “Marine Vivarium”’; and in the following year the guidebook to the Zoological Gardens called it the ‘Aquatic Vivarium’.
Within a year or two of this, however, the term aquarium had been coined and apparently established.
1830, noun use of neuter of Latin aquarius "pertaining to water," as a noun, "water-carrier," genitive of aqua "water" (see aqua-). The word existed in Latin, but there it meant "drinking place for cattle." Originally especially for growing aquatic plants; An earlier attempt at a name for "fish tank" was marine vivarium.