How do you write cynghanedd?

A line of cynghanedd is written with an invisible break or caesura in the middle that divides the line, for instance: X X X | X X X X. The cynghanedd is traditionally made up of seven syllables, so here “X” represents each syllable in a line.

What is a Welsh Englyn?

: a usually epigrammatic quatrain in Welsh poetry consisting of 30 syllables in lines of 10, 6, 7, and 7 syllables, the last three lines rhyming usually with the 6th syllable of the first line whose final syllable has no rhyme.