Celtiberian is an extinct Indo-European language of the Celtic branch spoken by the Celtiberians in an area of the Iberian Peninsula lying between the headwaters of the Duero, Tajo, Júcar and Turia rivers and the Ebre river.
This language is directly attested in near two hundred inscriptions dated in the 2nd century BC and the 1st century BC, mainly in Celtiberian script, a direct adaptation of the northeastern Iberian script, but also in Latin alphabet. The longest extant Celtiberian inscriptions are those on three Botorrita plaques, bronze plaques from Botorrita near Saragossa, dating to the early 1st century BC, labelled Botorrita I, III and IV (Botorrita II is in the Latin language).
The Botorrita plaque
Like in Welsh, there is an s-subjunctive, gabiseti "he shall take" (Old Irish gabid), robiseti, auseti. Compare Umbrian ferest "he/she/it shall make" or Ancient Greek? deiksēi (aorist subj.) / deiksei (future ind.) "(that) he/she/it shall show".