Reconstruction:Proto-Celtic/lubī

From Proto-Indo-European *lewbʰ- (“leaf”). Compare with English leaf and Latin liber (“book”).^[1]

*lubī f^[1]

1. herb, plant

• The only direct indication of inflectional class is Old Irish. On the surface, a declension with nominative luib, genitive singular lubae and Middle Irish luba(i) is hopelessly ambiguous between an original ī-stem and an ā-stem with a secondarily palatalized nominative singular.
• The deciding factor in favour of an original ī-stem over an ā-stem is the lack of a-affection in both Brittonic and Old Irish; in Old Irish for instance we would expect **lo(i)b instead of actual luib.
• The Brittonic forms do not exhibit i-affection, leading to Schrijver to reconstruct instead *lubis,^[2] and him to assume that in Old Irish, this word only secondarily joined the ī-stems because this word's feminine gender and non-genitive palatalization in the singular. Schrijver's reasoning is difficult to accept since many feminine i-stems exist in Old Irish, invalidating any motivation to even switch to the ī-stems in the first place.
• Instead, an easier way to unite the ī-stem inflection in Old Irish and the non-affection in Brittonic is to assume that Brittonic inherited the oblique stem *lubyā-, which would regularly lose its second syllable without any affections in Brittonic. This very strategy was used by Schrijver himself (albeit for different purposes) to unify the Brittonic derivatives of *nāwā (“boat”), via assuming an intermediate ī-stem *nāwī, oblique *nāwyā-.

• *lubīgortos

• Proto-Brythonic: *lluβ
  • ⇒ Old Breton: tutlub, tutlob
    • Breton: tulev, tule, tulo
• Old Irish: luib
  • Irish: luibh