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).