The epithet Τιαμου of the Moon-god in Lydia

This article discusses the origin of the epithet Τιαμου, which modifies the name of the Moon-god in a number of Greek inscriptions from Lydia dated to the 2nd–3rd century AD. All the etymological explanations provided so far will be taken into account, especially the Anatolian one, which, based on the existence of a Moon-god (κατα)χθόνιος, tries to establish a connection between Τιαμου and an Anatolian outcome of the PIE root for ‘earth’ (cf. Hitt. tēkan, Luw. tiyamm(i)-). After having discussed the arguments in favour and against both a Lydian and a Luwian origin, it will be argued that the latter seems to be most likely, although the possibility of a Lydian mediation remains.