A kenning is a compact figurative phrase that names something by indirect description instead of by its ordinary word. Common in Old English and Old Norse poetry, kennings often join two words into a striking image, such as whale-road for the sea or battle-sweat for blood. Poets use them to create compression, surprise, and a more elevated style.
In its simplest form, it comprises two terms, one of which (the 'base word'), is made to relate to the other to convey a meaning neither has alone.
Example
moon-harbor for the night sky
salt-road for the sea
storm-iron for a ship
battle-sweat for blood
"cannon-fodder" - soldiers, especially the war dead
"The devil's dandruff" - cocaine;
"Falling-over juice" - alcohol;
"The Game of Kings" - chess, horse racing and other sports;
[n] conventional metaphoric name for something, used especially in Old English and Old Norse poetry