Irish title of a document that may be known in English as the Fitness of Names or the Elucidation of Names. The treatise elucidates the significance and associations of many personal names from early Ireland in much the same way as the Dindshenchas deals with place-names. The title is also an epithet of Ana.
See Whitley Stokes, Irische Texte mit Übersetzungen und Wörterbuch, ser. iii, no. 2 (Leipzig: S. Hirzel, 1897), 285–444.