The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Metrical romance: A romance composed in verse. The term is sometimes associated specifically with verse romances of the Middle Ages, perhaps because the first metrical romances were medieval romances, which arose in twelfth-century France and then spread throughout Western Europe. More broadly defined, however, the metrical romance persisted into the nineteenth century, when it was eclipsed by romances written in prose.
EXAMPLES: The anonymous fourteenth-century English medieval romance Sir Gawain and the Green Knight; George Gordon, Lord Byron’s The Giaour (1813).