When a poet refers to something by one of its characteristics rather than its name - for example, referring to a country's 'strength' rather than 'armies' - it is known as metonymy. It differs from synecdoche, in that these are abstract qualities rather than concrete parts.

Les Murray's 'Annals of Sheer' opens with an image of a sheep track that "winds / around buttress cliffs of sheer" - it is the slope that is sheer, but through metonymy its fearsome steepness is made more important than it being a cliff.

Kevin Crossley-Holland uses metonymy when he writes "give me the gruff", rather than "give me the gruff things", in 'The Grain of Things'.