An Etymological Dictionary of Astronomy and Astrophysics

1. The solid form of water; it is found in the atmosphere as snow crystals, hail, ice pellets, etc., and on the Earth’s surface in forms such as frost, rime, glaze, glacier ice, etc.
   
2. The solid, frozen form of gases in cold astronomical objects.

Etymology (EN): Ice, from O.E. is “ice,” from P.Gmc. *isa-; cf. O.N. iss, O.Fris. is, Du. ijs, Ger. Eis. Cognate with Pers. yax, as below.

Etymology (PE): Yax, from Av. aexa- “ice, frost,” isav-, isu- “icy, chilly;” cf. Sarikoli (Pamir dialect) īš “cold;”
P.Gmc. *isa-, as above.