*Isaz is the reconstructed Proto-Germanic name of the i-rune ᛁ, meaning "ice".
The rune is recorded in all three rune poems: Anglo-Saxon ᛁ Is bẏþ oferceald, ungemetum slidor, glisnaþ glæshluttur gimmum gelicust, flor forste geƿoruht, fæger ansẏne.
Ice is very cold and immeasurably slippery; it glistens as clear as glass and most like to gems; it is a floor wrought by the frost, fair to look upon.
Old Icelandic ᛁ Íss er árbörkr ok unnar þak ok feigra manna fár.
Old Norwegian ᛁ Ís kǫllum brú bræiða; blindan þarf at læiða.