downfall, precipitation - the falling to earth of any form of water (rain or snow or hail or sleet or mist)

H2O, water - binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent

crystal - a solid formed by the solidification of a chemical and having a highly regular atomic structure