Old Irish is a member of the Celtic branch of Indo-European languages. Besides the ogam inscription, dating to the 4th century AD, and glosses in Latin literature from the 8th century, it is attested in books from the 12th century AD. Its entire corpus is very extensive, covering hundreds of manuscripts containing stories of the saints, commentaries to the Scripture, hymns, poetry, historical literature etc.

As the language is attested as late as in the second millenium AD, the examples of adjective valence are not considered here.