Background: Hallucinations are a pathognomonic symptom of schizophrenia and other severe psychotic disorders. Despite being the source of many severe personal and socio-economic problems, providing an effective, efficient and ethically-informed treatment is still one of the main unresolved issues in psychiatry and psychology, according to the National Institute for Health and Care Excellence. In our opinion, this might be partially due to certain long-standing inconsistencies in the definition of the notion of u201challucinationu201d itself, which could in turn mislead our attempts to provide an effective treatment. Therefore, our main purpose was to examine the current standard conceptualization of hallucinations and to track its historical roots in order to determine its conceptual architecture as well as to explore other alternative conceptualizations.Methods: We conducted a historical review of the concept of hallucination, focusing our research in the works of 19th and early to mid-20th century authors such as Esquirol, Baillarger, Tamburini, Bleuler, Kraepelin, Ey and others. Specifically, our analysis aimed at determining the different axes that had structured the historical debate on the concept of hallucinations.Findings: We distinguished two main themes of debate: the first one regarding the natural ontology and aetiology of hallucinations, and the second one regarding its alleged semantical content. As to the first one, we distinguished between cognitive-driven conceptualizations (i.e., hallucinations conceived as u201cperceptual delusionsu201d) and sensory-driven conceptualizations (i.e., hallucinations conceived as u201csensorimotor disturbancesu201d). Among the second, we distinguished between meaningful-driven approaches (i.e., those that grant hallucinations with personal history-related content) and meaningless-driven approaches (i.e., those that do not grant hallucinations with any kind of semantic content).Discussion: we believe that this historical review provides a certain clarification of the different ways in which hallucinations have been conceived throughout their nosological history. This might in turn serve as a starting point for further conceptual analyses aimed at establishing the logical validity and philosophical commitments of each conceptual model. Finally, this could allow clinical psychologists and other practitioners to better operationally define these phenomena and consequently determine the best way to deal with them in the least invasive and most efficient way possible.