ice crystal
solid frozen water molecules
snowflake
single ice crystal or an aggregation of ice crystals which falls through the Earth's atmosphere
soft rime
fragile deposit of ice formed by freezing fog
ice pellets
precipitation of transparent, spherical or irregular particles of ice
frazil ice
ice crystals that form in supercooled water that is too turbulent to permit coagulation into sheet ice
hoar frost
version of frost