Guo Pu
Classical Chinese and Japanese literature contains many Chinese characters that feature only once in the corpus, and their meaning and pronunciation has often been lost. Known in Japanese as , literally "lonely characters", these can be considered a type of "hapax legomenon". For example, the "Classic of Poetry" (c. 1000 BC) uses the character 篪 exactly once in the verse "伯氏吹埙，仲氏吹篪", and it was only through the discovery of a description by Guo Pu (276–324 AD) that the character could be associated with a specific type of ancient flute.