The term “kirakira name” has been broadly used in Japan. However, the definition of this term is ambiguous, and what it means is not sufficiently clear. This lack of clarity has caused misunderstandings, insufficient understandings, and unnecessary disputes, which have led to the constriction of appropriate communications, productive discussions, and accumulations of scientific findings, both in society at large and in academic fields. Therefore, this article clarified the definitions of kirakira names and the components of these definitions by exploring representative dictionaries and encyclopedias. Analyses showed that only one component was consistently found among all the definitions: “low-frequency names.” Thus, the broad definition of kirakira name is “low-frequency names.” Moreover, three components were found in not all but some of the definitions: (1) “names that deviate from traditions,” (2) “names that are difficult to read,” and (3) “names that are used in positive or neutral contexts.” Thus, the narrow definition of kirakira name based on these three components is “low-frequency names that deviate from traditions and are difficult to read (when Chinese characters are used), which are used in positive or neutral contexts.” This article is important because it clarifies the definition of kirakira name, which has been ambiguously understood and separately discussed, and it also provides fundamental and sharable definitions of kirakira names. In addition, this article shows that definitions of kirakira names and their components differ even among representative dictionaries and encyclopedias. Therefore, before discussing kirakira names, it is recommended that people explain their intended definition of kirakira names or at least what they mean.
