In literature, a kenning is a poetic phrase substituted for the usual name of a person or thing. For example, the sea in Old English was called the whale's road.
The word is derived from the Old Norse phrase kenna eitt við, "to express a thing in terms of another", and is prevalent throughout Norse, Old English and Celtic literature. Kennings are especially associated with the practice of alliterative verse, where they tend to become traditional fixed formulas.
A list of kennings may be consulted for reference purposes.
A notable peculiarity of kennings is the possibility to construct complicated kennings by means of consecutive substitution. For example, those who are keen in kenning readily know that slaughter dew worm dance is battle, since slaughter dew is blood, blood worm is sword, sword dance is battle.
Another kind of wordplay is based on the inversion of kennings. For example, if sword dance is battle and spear-din is another kenning for battle, then sword may easily become "spear-din dancer".
See also: synecdoche, metonymy.