Celtiberian (or Hispano-Celtic) is a member of the (continental) Celtic branch of the Indo-European language family.  It was spoken in the Iberian peninsula and written in Iberian script. It is attested in 200 inscriptions from 2nd and 1st century BC, written in Celtiberian script and in Latin alphabet. The longest inscriptions are on three Botorrita plaques. Botorrita I is the longest inscription, consisting of eleven lines.

The word order is SOV. Nominals could inflect in two numbers (singular, plural) and possibly dual, for three genders (feminine, masculine, neuter) and in eight cases (nominative, accusative, genitive,dative, locative, instrumental, ablative, vocative). All forms are not attested for all of the Continental Celtic languages. It did not use infinitives but nominalized verbs (three attested in Celtiberian, Eska 2008:178). Participles were more frequent – there were the present active, mediopassive and passive participles.

As the language is poorly understood and attested, there is no known example of adjective valence.

Bibliography:

Eska, Joseph F.  and Ellis D. Evans. 2010. Continental Celtic. In: Martin J. Ball and Nicole Müller (eds.), The Celtic languages. London &New York: Routledge, p. 28-54.

Eska, Joseph F. 2008. Continental Celtic. In: Woodard, Roger (ed.), The Ancient Languages of Europe. Cambridge: Cambridge University Press, p. 165-188.

Untermann, Jürgen. 1997. Monumenta Linguarum Hispanicarum. IV Die tartessischen, keltiberischen und lusitanischen Inschriften, Wiesbaden.

Wodtko, Dagmar S. 2003. An Outline of Celtiberian Grammar.