kenning (n.) Look up kenning at Dictionary.com
Old English cenning "procreation; declaration in court," present participle of ken (v.). From early 14c. in senses "sign, token; teaching, instruction;" c.1400 as "mental cognition." From 1871 as "periphrastic expression in early Germanic poetry;" in this sense it probably is from a modern learned use of Old Norse cognate verb kenna "to know, to recognize, to feel or perceive; to call, to name (in a formal poetic metaphor)."
In the whole poem of Beowulf there are scarcely half a dozen of them [similes], and these of the simplest character, such as comparing a ship to a bird. Indeed, such a simple comparison as this is almost equivalent to the more usual "kenning" (as it is called in Icelandic), such as "brimfugol," where, instead of comparing the ship to a bird, the poet simply calls it a sea-bird, preferring the direct assertion to the indirect comparison. [Henry Sweet, "Sketches of the History of Anglo-Saxon Poetry," London, 1871]