fluellin
Any of various varieties of Veronica, especially Veronica officinalis; speedwell.
countable, obsolete, uncountable
There is another sort of Lluellin which has longer branches wholly trailing upon the ground two or three foot long and sometimes more, thinner set with leaves thereon, upon small footstalks.
Where it comes from
From Welsh llysiau Llewellyn, literally Llewellyn's herbs.
Adapted from the Wiktionary entry fluellin (CC BY-SA 4.0).