In Norse mythology

Norse mythology

Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

, Gleipnir (Old Norse

Old Norse

Old Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....

 "open one") is the binding that holds the mighty wolf Fenrisulfr (as attested in chapter 34 of the Prose Edda

Prose Edda

The Prose Edda, also known as the Younger Edda, Snorri's Edda or simply Edda, is an Icelandic collection of four sections interspersed with excerpts from earlier skaldic and Eddic poetry containing tales from Nordic mythology...

book Gylfaginning

Gylfaginning

Gylfaginning, or the Tricking of Gylfi , is the first part of Snorri Sturluson's Prose Edda after Prologue. The Gylfaginning deals with the creation and destruction of the world of the Norse gods, and many other aspects of Norse mythology...

). The Gods had attempted to bind Fenrir twice before with huge chains of metal, but Fenrir was able to break free both times. Therefore, they commissioned the dwarves to forge a chain that was impossible to break. To create a chain to achieve the impossible, the dwarves fashioned the chain out of six impossible things:

• The sound
  Sound
  Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
  
   of a cat
  Cat
  The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
  
  's footfall
• The beard
  Beard
  A beard is the collection of hair that grows on the chin, cheeks and neck of human beings. Usually, only pubescent or adult males are able to grow beards. However, women with hirsutism may develop a beard...
  
   of a woman
  Woman
  A woman , pl: women is a female human. The term woman is usually reserved for an adult, with the term girl being the usual term for a female child or adolescent...
  
  
• The root
  Root
  In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
  
  s of a mountain
  Mountain
  Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
  
  
• The sinews of a bear
  Bear
  Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
  
  
• The breath of a fish
  Fish
  Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
  
  
• The spittle of a bird
  Bird
  Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
  
  

Therefore, even though Gleipnir is as thin as a silk

Silk

Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

en ribbon

Ribbon

A ribbon or riband is a thin band of material, typically cloth but also plastic or sometimes metal, used primarily for binding and tying. Cloth ribbons, most commonly silk, are often used in connection with clothing, but are also applied for innumerable useful, ornamental and symbolic purposes...

, it is stronger than any iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 chain

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

. It was forged by the dwarves in their underground realm of Svartálfaheim.

Gleipnir, having bound the Fenrisúlfur securely, was the cause of Týr's lost hand, for the Fenrisulfr bit it off when he was not freed. Gleipnir is said to hold until Ragnarök

Ragnarök

In Norse mythology, Ragnarök is a series of future events, including a great battle foretold to ultimately result in the death of a number of major figures , the occurrence of various natural disasters, and the subsequent submersion of the world in water...

, when it will break and Fenrir will devour Odin

Odin

Odin is a major god in Norse mythology and the ruler of Asgard. Homologous with the Anglo-Saxon "Wōden" and the Old High German "Wotan", the name is descended from Proto-Germanic "*Wodanaz" or "*Wōđanaz"....

.