-arium

1.
a suffix occurring in loanwords from Latin, which often denote a location or receptacle (armarium; caldarium; solarium; vivarium). It has limited productivity in English, especially in words denoting an artificial environment for plants or animals, on the model of vivarium or herbarium: aquarium; insectarium; terrarium.
Compare -ary.
Origin
< Latin -ārium; see -ary
British Dictionary definitions for -arium

-arium

suffix
1.
indicating a place for or associated with something: aquarium, planetarium, solarium
Word Origin
from Latin -ārium, neuter of -ārius-ary