Linguistic ambiguity is a quality of language that makes speech or written text open to multiple interpretations. That quality makes the meaning difficult or impossible for a person or artificial intelligence (AI) program to reliably decode without some additional information.
Lexical ambiguity often occurs because words and phrases can have multiple meanings. For example, the meaning of “We saw her duck” could be either that the writer saw a woman crouch to avoid a missile or that they saw a duck that belonged to the woman.
Structural ambiguity arises when the order of words or phrases in content result in multiple possible interpretations. Misplaced modifiers are a common example. Words and phrases are understood to modify the nouns and pronouns that are assigned to them. When they are misplaced, a sentence can be interpreted to mean something other than what the writer intended.
Figurative language can also be a problem for the interpretation of speech or writing, particularly for non-native speakers and natural language processing (NLP) software. Figurative language includes figures of speech such as metaphor, irony, idioms and puns, as well as imagery and sound-based devices, many of which pose their own particular types of challenges for comprehension.
Ambiguity is distinct from the related problem of vagueness, which can be thought of as a lack of specificity that hampers interpretation. Rather than a multiplicity of meanings, vagueness in language may make it difficult to assign any meaning at all.