An "englyn" is a form of traditional Welsh poem. There are eight forms of englyn, this one following the style of "Englyn unodl union".
This is a straight englyn with one rhyme. It consists of four lines. The first line consists of ten syllables, the second line of six syllables the third and fourth lines consist of seven syllables each.
The seventh, eighth or ninth syllable of the first line introduces the rhyme and this is repeated on the last syllable of the other three lines. The last syllable of the first line should rhyme with a syllable early in the second.
DYN CREFYDDOL WREIDDIOL RIN-HYD ELOR
CAED WILLIAMS BRYNCETHYN;
O'I ÔL EF MAE HIRAETH BLIN
DAEARWYD FFRYND Y WERIN.
The above englyn was written by Watcyn Wyn.
The Wikipedia website referrs to the Canadian novelist, Robertson Davies (b.1913), who claimed that englyns were an old enthusiasm of his. He said that the form was derived by the Welsh from the inscriptions on Roman tombs in Wales.