In Welsh poetry, an awdl is a long poem in strict metre. Originally, an awdl could be a relatively short poem unified by its use of a single end-rhyme, using cynghanedd; such early awdlau are associated with the Cynfeirdd such as Aneirin and Taliesin as found in collections such as the Book of Taliesin, the Black Book of Carmarthen, the Hendregadredd Manuscript or The Red Book of Hergest. By the nineteenth century however it came to its modern definition as a long poem using at least two of the twenty-four recognised "official" strict forms.