Celtiberians spoke a language inherited from Continental Celtic, related to Gaulish and Lepontic. But the main distinguishing feature of the subsequent tongue they used is that Celtiberians acquired much of their phonetics and lexics from non-Indo-European Iberian languages, this reflected in placenames and names of deities. Nevertheless we can state with certainty that the language belonged to Q-Celtic, and so Indo-European *kw- grew into q here. In fact the structure of Celtiberian grammar remained completely Celtic. The nouns are inflected, having sometimes a sibilant -s' instead of Indoeuropean *-s. The language used about five or six cases (with accusative, dative, instrumental); the dative plural had the Italo-Celtic -b- suffix following the stem. The plural nominative either preserves Indo-European *-es or develops an "European" -i. There is also one strange ending for the genitive singular: -o, which is rarely seen anywhere else in the Indo-European family.
Only two verbs are known from Celtiberian, but they witness clearly that verb endings remained Indo-European, with -t in the 3rd person singular and -nti (a primary ending) in 3rd person plural.
Celtiberians were easily assimilated by Romans in the last few centuries
B.C. and their language, the product of a mixture of different language