William Empson defined ambiguity as: 'any verbal nuance, however slight, which gives room for alternative reactions to the same piece of language'. Although ambiguity is not desirable in prose, in poetry it can sometimes add extra layers of meaning. Figurative language - such as metaphors - often create ambiguity. In 1930 Empson published a critical work entitled Seven Types of Ambiguity.
[n] unclearness by virtue of having more than one meaning
[n] an expression whose meaning cannot be determined from its context