imbricationn.

imbrication (n.)1640s, from French imbrication, from Latin imbricare "to cover with tiles," from imbricem (nominative imbrex) "curved roof tile used to draw off rain," from imber (genitive imbris) "rain," from PIE *ombh-ro- "rain" (cognates: Sanskrit abhra "cloud, thunder-cloud, rainy weather," Greek ombros "rain"), from root *nebh- "moist, water" (see nebula).