A Rhupunt hir is merely a Rhupunt that is NOT broken into short stanzas.
Structure, Metrical Requirement, Rhyme Scheme Requirement, Stanzaic
(RHEE-pint) This is a syllabic line of three to five tetrasyllabic sections. It is sometimes presented as stanzas (tercets, quatrains, quintets) rather than one line. The main rhyme can change after two or more lines. The internal rhyme can be consonance instead of true rhyme.
xxxa xxxa xxxa xxxb
xxxc xxxc xxxc xxxb
xxxd xxxd xxxd xxxb, etc.
xxxa xxxa xxxa xxxa xxxb
xxxc xxxc xxxc xxxc xxxb
xxxd xxxd xxxd xxxd xxxb, etc.
xxxa xxxa xxxb
xxxc xxxc xxxb
xxxd xxxd xxxb, etc.
Pasted from <http://www.poetrybase.info/forms/002/221.shtml>
Thanks to Charles L. Weatherford of PoetryBase
Related Welsh Form are HERE.