Periphrasis is the use of several words to express something that could be said more directly. In poetry, writers often use it to sound elevated, formal, playful, or indirect, sometimes naming a person, object, or idea through a descriptive phrase instead of a plain term. It is broader than a kenning, which is a special kind of metaphorical compound or phrase.
Example
The moon became the silver lantern of the night,
And sleep came softly over the windowed house.