Seizure precipitation is a defining characteristic of reflex seizures and epilepsies, but seizure precipitants are also commonly reported for patients with epilepsies not considered to be reflex in nature. This raises the questions of exactly how reflex and nonreflex epilepsies with seizure precipitants are defined, and how these concepts are differentiated from one another in current practice. In this systematic literature review, definitions of reflex seizures, reflex epilepsies, and precipitation in a nonreflex context were extracted from published primary research papers. Content analysis was applied to these definitions to identify their main features, allowing comparisons to be made between definitions of the different concepts. Results indicated that there was little consistency within definitions of a given term, and that although some differences in definition content were found between terms, it was evident that clear defining characteristics to differentiate them from one another were lacking. These findings are discussed in the context of current debates regarding classification of the reflex epilepsies and the extent to which the distinction between reflex and nonreflex epilepsies is a meaningful one. Suggestions are made for how clarity might be increased in ongoing research in this area.