Hagalaz is the ninth rune of the Elder Futhark and the first of the second aett, the group often named for Hagal or Heimdall. It carries the phoneme "h" and its reconstructed name means hail. The rune poems describe hail as the whitest of grains that falls from heaven, driven by wind, then melts into water, an image of a destructive force that nonetheless turns to something life-giving.
Hagalaz opens the aett of Hagal, sometimes called the aett of Heimdall, the Elder Futhark's second eight-rune group. Its Old English futhorc counterpart, haegl, meaning hail, receives a stanza in the Old English Rune Poem describing hail as the whitest of grains, whirled from the vault of heaven, tossed by gusts of wind, before it turns to water. Hagalaz survived into the Younger Futhark as hagall, keeping the hail sense, and appears in both the Norwegian and Icelandic Rune Poems as well.
Runologists reconstruct the Proto-Germanic form behind the name as *hagalaz, part of the comparative linguistic evidence, alongside cognate vocabulary across the older Germanic languages, used to establish the name's original sense independent of the later rune poems themselves. Hail's destructive but transient character, damaging yet melting away, is a natural image rather than a moralised one in every surviving account of it.