insectarium (n.)

c. 1600, from Latin (animal) insectum "(animal) with a notched or divided body," literally "cut into," noun use of neuter past participle of insectare "to cut into, to cut up," from in- "into" (from PIE root *en "in") + secare "to cut" (from PIE root *sek- "to cut"). The Latin word is Pliny's loan-translation of Greek entomon "insect" (see entomology), which was Aristotle's term for this class of life, in reference to their "notched" bodies.

First in English in 1601 in Holland's translation of Pliny. In zoology, in reference to a class of animals, 1753. Translations of Aristotle's term also form the usual word for "insect" in Welsh (trychfil, from trychu "cut" + mil "animal"), Serbo-Croatian (zareznik, from rezati "cut"), Russian (nasekomoe, from sekat "cut"), etc. Insectarian "one who eats insects" is attested from 1893.

Among the adjectival forms that have been tried in English (and mostly rejected by disuse) are insectile (1620s), insectic (1767), insective (1834), insectual (1849), insectine (1853), insecty (1859), insectan (1888).

It is curious that in the eyes of the Anglo-Saxon naturalists, the frog, the toad, the lizard or eft (efte), and other reptiles, were usually placed under the head of insects ; and this odd classification was preserved to rather a late period. [Thomas Wright, "Anglo-Saxon and Old English Vocabularies," 1884]

1830, "artificial pond in a garden or elsewhere for growing aquatic plants," noun use of neuter of Latin aquarius "pertaining to water" (also, as a noun, "water-carrier"), genitive of aqua "water" (from PIE root *akwa- "water").

The noun aquarium in Latin meant "drinking place for cattle." In English, the meaning "vessel of glass filled with water in which living aquatic animals are kept indoors" is by 1853. The Victorian mania for indoor aquariums began with the book "The Aquarium," published 1854 by English naturalist Philip Henry Gosse. An earlier attempt at a name for "fish tank" was marine vivarium.