• TECHNICAL NAME USED IN ACADEMIC STUDIES: The Valknot/Gierröd symbol is called the Ternary Trigonal Knot and/or Ternary Triangular Knot which is abbreviated as the compound word "Tertrigon" or “Tertrigonal Knot” and is the common vernacular for academics that study & conduct research pertaining to  this ancient symbol.

• BASIC and MODERN MEANING: Devotion to Heathen Religion/Gods, specifically Odin/Wotan/Allfather.

• IT'S CRYPTIC and RITUAL MEANING: Nine (9), from the lore associated with it in the Edda; for the Nine (9) days/nights Odin hung on a tree, wounded by his own Spear. Ritual performed to be bound and belong to Odin/Wotan. Symbolic of being marked for/bound to Odin and Valhall in death and the afterlife. 

• HISTORICAL ORIGIN: Nine ritual spear-cuts/wounds—made with a spear-tip—by ancient Heathen Warriors on their own bodies; represented as icons/symbols found on archaeological grave goods and burial artifacts.  Ancient Roman historical documents (Vindolanda 85-122CE) have instances and references to the "Barbarian Nine (9)" symbol found on laeti and foederati Germanic soldiers, also comments by or attributed to Roman Military Commanders about the superior combat skills and ferocity of these Heathen soldiers who bore the Gierrod (Valknut); these Commanders also advised other Commanders to give preference in recruiting these Germanic soldiers (that had the 'Allemanni Novem' marks on their body) and retaining them in Roman military units. 

“To Odin then true-fast

Carves he fair runics,—

Death-runes cut deep on his arm and his breast.”

—Viking Tales of the North (R. B. Anderson).

"He had himself marked with a spear and assigned to himself the weapon-dead men, and said he would go to Goðheimar and be reunited with his friends there."

--Ynglinga saga 8, Heimskringla I

• MYSTICAL and ESOTERIC MEANING: Protection granted by Odin from Enemies; Blessing from Odin for Victory in Battle. The symbol traditionally appears colored blood red.

• VALKNUT ETYMOLOGY: A kenning meaning belonging to, or bound to, or marked by Odin/Wotan; A Compound of two words, each meaning "Choice\Elect" and "Binding\knot"; "CHOSEN\ELECT": Old Norse val, Proto-Germanic *walō. "FASTENING\KNOT": Proto-Germanic *knuttan-, Old Frisian knotta, Dutch knot, Old High German knoto, German Knoten, Old Norse knutr, from Proto Indo-European *nōdo-.

• Despite many assertions, the symbol has no relation to "Hrungnir's Heart" as written in the story of Skáldskaparmál. The only thing that the Tertrigon and "Hrungnirs Heart" have in common is a triangular shape.

• Geirröd/GIERRÖD : [Proto-Germanic]—a spear, [Edda 41, FmS. i. 177, Hm. 15, 37, Hkv. 1. 15,Hbl. 40]; Odin is represented wielding a geir, called Gungnir, as are also the Valkyrjur; Marka sik geirs-oddi: "to mark oneself in the breast with a spear’spoint," so as to make blood flow, was a Heathen rite whereby warriors on their death-bed devoted themselves to Odin; it was the common belief that a man who died a natural death of old-age was not admitted into Valhall upon dying; this rite is only mentioned in mythical Sagas such as Yngling Saga ch. 10;  also Gautreks Saga ch. 7.—þá stakk Starkaðr sprotanum á konungi ok mælti, nú gef ekþik Óðni: the origin of this rite is in Havamal, where Odin himself is represented as hanging on the tree Yggdrasil "Wounded with a spear and given to Odin, myself to myself." 

• GIERRÖD ETYMOLOGY: A kenning for devotional self-inflicted spear cuts or wounds to Odin/Wotan; A Compound of two words, each meaning "Spear" and "Red"; "SPEAR": Proto-Germanic *gaizaz, Old High German gêr, Old English gâr, Old Norse gierr, from a Proto-Indo-European root *sper- 'spear, pole'...  "RED" or "RÖD": Proto-Germanic *raudaz, Old English rēad, Dutch rood, and German rot, from an Indo-European root shared by Sanskrit rudhira ‘red’.

• There is further speculation that this symbol represents Ijodasmiðr, which is the kenning for Odin/Wotan’s power to craft & deploy charms/spells. This understanding is drawn from a parallel comparison between Thor's Fylfot/Swastika and Odin's Valknot/Tertrigonal-Knot... The symbol of the Fylfot/Swastika is a known, ubiquitous semiotic symbol for Thor/Perkunaz and his might & power to control weather; therefore, it is highly probable that—like the Thunder God—Allfather has his own ubiquitous, semiotic symbol representing himself & his aforementioned powers, which must be the Valknot/ Tertrigonal-Knot.

• OTHER USAGE AND MEANINGS: Symbol of Odin's magic, spells, and charms. A curse to bind your enemies. Symbol for the Slain in Battle. Symbol for a sacrifice to Odin. Having deep and ancient religious ties to the Tripartition of the Cosmic Order of the Gods & Goddesses.

• Other Vernacular Designations: Valknutr; Geirröd; Wotans-Knot; Odins-Knot; Odins-Charm; Allfather's-Bond; Heathen-Nine; Knot-of-the-Fallen; Knot-of-the-Dead; Tertri-Knot; Tri-Thirds; Þrí-deila; Tertrangle. Which most likely have a connection to a similar symbol called the Trilete / Triquitrite / Triquetra...