Tiwaz is the seventeenth rune of the Elder Futhark and the first of the third aett, the group named for the god Tyr. It carries the phoneme "t" and its reconstructed name is that of the god himself, an early Germanic sky and war deity associated with law, oaths and justice. Its arrow-like shape points upward, and the rune poems link it to a sure guiding star that keeps faith through the night. In Norse myth Tyr loses a hand binding the wolf Fenrir, an act read as justice bought by sacrifice.
Tiwaz opens the aett of Tyr, the Elder Futhark's third and final eight-rune group, named for the god whose own name the rune carries. Its Old English futhorc counterpart, tir, receives a stanza in the Old English Rune Poem describing it as a guiding star, faithfully keeping troth with noblemen, ever on its course over the mists of night, never fails. Tiwaz survived into the Younger Futhark as tyr, and appears in both the Norwegian and Icelandic Rune Poems, the latter explicitly naming the god and calling him the one-handed among the gods, a reference to the myth of Tyr's hand lost binding the wolf Fenrir.
Runologists reconstruct the Proto-Germanic form behind the name as *tīwaz, 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.