The Andvari Iconographic Thesaurus (AIT) is a set of terms and their definitions organized into an ontological network that can be used to describe the iconography of art produced in early medieval northern Europe (4th-12thcenturies). It has been applied to the present digital catalogue of the picture stones in order to enable searchability by iconographic features. The AIT was designed specifically to capture the northern tradition, and therefore it is different from other indexes or controlled vocabularies (e.g., the Index of Medieval Art). It was developed as part of the larger Project Andvari, an ongoing digital humanities project to create an online portal for searching simultaneously multiple collections of early medieval northern art and artifacts.

The thesaurus is currently available as a plug-in for other digital projects. Thesaurus development and the tagging of picture stone entries have been carried out by Lilla Kopár (The Catholic University of America), Beth Newman Ooi (The Catholic University of America), and Nancy L. Wicker (The University of Mississippi).