A kenning is a much-compressed form of metaphor, originally used in Anglo-Saxon and Norse poetry. In a kenning, an object is described in a two-word phrase, such as 'whale-road' for 'sea'. Some kennings can be more obscure than others, and then grow close to being a riddle. Judith Nicholls' 'Bluebottle' uses kennings as part of a larger poem, that is itself a riddle; Andrew Fusek Peters and Polly Peters go further, building a pair of poems both consisting entirely of kennings.
The 'word-fisher' in Kevin Crossley-Holland's 'Beachcomber' is a kenning for a poet; the title itself may once have been a kenning, although it has now ceased to be one, as it is so established a word that its metaphorical weight has been lost.