The rinnard or roinnard is an Irish poetic form.
It has the following guidelines:
An example first:
Quatrain (or four-line) poem (or stanzas).
Two-syllable rhymes at the end of each line.
Rhyme scheme for each quatrain: abcb.
The “a” and “c” words consonate with the “b” words
Usually an alcill rhyme between lines three and four.
Note on aicill rhyme:
An aicill rhyme in this poem means that the final syllable of line three rhymes somewhere in line four (usually the middle).