-arium

-arium

suff.
A place or device containing or associated with: planetarium.

[Latin, neuter of -ārius, -ary.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

-arium

suffix forming nouns
indicating a place for or associated with something: aquarium; planetarium; solarium.
[from Latin -ārium, neuter of -ārius -ary]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

-arium

a suffix occurring in nouns denoting an artificial environment for plants or animals, on the model of vivarium or herbarium: aquarium; terrarium. Compare -ary.
[< Latin -ārium; see -ary]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.