Boyd’s Bible Dictionary:

The seventh plague
(Ex. 9:18-29). God’s weapon (Josh. 10:11; Rev. 16:21).

Concise Bible Dictionary:

Particles of ice falling from the clouds. Though hail is usually formed by natural causes not yet perhaps well understood, it is often referred to in scripture as one of the judgments of God. It formed one of the plagues in Egypt (Ex. 9:18-34; Psa. 78:47-48; Psa. 105:32); and is at times connected with fire or lightning. God smote the Amalekites by “great stones” from heaven (Josh. 10:11). The hail is called upon to praise Jehovah, because it fulfills His word (Psa. 148:8; Isa. 28:2,17; Hag. 2:17). It will also form a notable part of the judgments of God in His future dealings with this guilty world (Rev. 8:7; Rev. 11:19; Rev. 16:21).

Strong’s Dictionary of Hebrew Words:

a primitive root, to hail
KJV Usage: