ETYMOLOGY
from im- + pluvious (characterized by rain, rainy) [from French pluvieux, or from Latin pluviosus (rain)]
EXAMPLE
“…Though (by the way) how that Expression should countenance an Impluvious state before the Flood, as the Latin Theory would make it, is not so clear and easie to be understood. For, if we consider, there was no Water upon that Earth, but what fell in Rain…”
From: Geologia: Or, A Discourse Concerning the Earth before the Deluge
By Erasmus Warren, 1690
Lexicophilia 