Impluvium is a related term of compluvium.
In architecture terms the difference between compluvium and impluvium
is that compluvium is a space left unroofed over the court of a dwelling in Ancient Rome, through which the rain fell into the impluvium or cistern while impluvium is a low basin in the center of a household atrium, into which rainwater flowed down from the roof through the compluvium.
compluvium
English
Noun
(compluvia)
(architecture) A space left unroofed over the court of a dwelling in Ancient Rome, through which the rain fell into the impluvium or cistern.
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impluvium
English
Noun
(en-noun)
(architecture) A low basin in the center of a household atrium, into which rainwater flowed down from the roof through the compluvium.
References
Soprintendenza archeologica di Pompei [http://www2.pompeiisites.org/database/pompei/pompei2.nsf/pagine/AF1D1410A62DB415C1256AB6003528F6?OpenDocument]
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