Ambiguity is conventionally defined in Linguistics as a property of a word or an utterance that has two meanings or two interpretations, and is usually classified as lexical, morphological, syntactic (or structural), and pragmatic. Giving an adequate definition of linguistic ambiguity is not trivial, nor is there unanimity in accepting it. Most researchers tend to agree that ambiguity should be distinguished from related concepts such as vagueness, context sensitivity, reference transfer, and underdetermination or generality of meaning. The distinction between these concepts is also related to the divergences or connections between the perspectives of analysis of ambiguity, and the aim of each work. In this introduction, we define the limits of ambiguity with respect to related concepts and summarize the studies contained within this special issue. These studies do not cover all possible approaches to linguistic ambiguity, but provide a broad overview that can be useful in different fields. We trust that they will contribute to deepening into a phenomenon that is not yet well described and that seems to be consubstantial with the use of language.