Structural ambiguity is caused in a language’s syntax as a result of a its grammar. Specifically, varied interpretations arise because the grammar can assign two (or more) different structures to the same word combination, even if none of the words within it are lexically ambiguous. (Kroeger, 2018, p. 23)
Kroeger, P. R. (2018). Analyzing meaning: An introduction to semantics and pragmatics. Language Science Press.