Details:
ärür was the third-person present or aorist form of är- and functioned as an overt copula meaning ‘is’. As a distinct form, it disappeared from most modern Turkic languages, and its functions were redistributed. In ordinary present-tense nominal clauses, many languages now leave the third-person copula unexpressed. In the few Turkic languages where an overt copular marker is used, it is often a continuation of turur ‘stands; is’, rather than of ärür; this is the origin of Azerbaijani -dır/-dir/-dur/-dür. In Azerbaijani Turkish this marker is commonly used as a third-person predicate marker.