A kenning is a characteristic rhetorical device of Old English poetry (and Old Norse). The typical kenning is a compound in which each element identifies an attribute through the figures of metaphor, synecdoche, and metonymy. It works by indirection. An Old English poem, for example, might call a sword a "battle-light" (hilde-leoma), because the polished steel gleams like a light (metaphor) and it is used for fighting (metonymy). Or it might call the human body a “bone-house” (ban-hus), where “bone” works by synecdoche and “house” by metaphor.
Before going further, be sure to review the tropes of metaphor, metonymy, and synecdoche. Pay special attention to the distinction between metonymy and synecdoche. More expansive treatments can be found in the Princeton Encyclopedia of Poetry and Poetics.
Modern English has its share of kennings, especially if we expand the pool to include two-word phrases. For example, cigarettes have been called "coffin nails": "coffin" works by metonymy (lung cancer kills) and "nails" by metaphor (a cigarette resembles a nail in shape). Another example is "greasy spoon" for a downscale diner, where "greasy" connotes unhealthy fats and poor standards of cleanliness and "spoon" connotes eating. An argument can be made for “greasy” and “spoon” to work either as a synecdoche or a metonymy, and the exercise below asks you to make a case for one or the other. Whatever you decide, the important thing is to recognize that “greasy spoon” works by figural substitution. To put it another way, a literal reading of "greasy” and “spoon," whether as individual words or together as a phrase, does not indicate a place where people eat.
Not every clever phrase or compound is a kenning. "Pothole" would not make the list because even though "pot" is a metaphor, the hole is a hole. A sweatshop is a shop. A trophy wife is a wife. “Gridiron” meaning “football field” would not work because the compound as a whole is a metaphor, not its constituent parts. Same with “douchebag” or “scumbag” as an insult.
Print out the attached pdf and follow the instructions. It ends by asking you to list kennings that you know.