The origin of the OFrk *Lôhar is from the PGmc *Lauhaz meaning “clearing, meadow”. *Lauhaz is in turn derived from the PIE *lówkos (clearing), which also gave rise to the Latin lucus used to denote a sacred grove. There appears to be a semantic relation or conflation between *lówkos and PIE *lewk (bright), where the former is descendant of the later. In any case, the comparison or relation between “clearing/meadow” and “light/bright” is much older than philologists can untangle. This presents an ancient affinity between “light” and “leah”. If one takes the example of the Gaulish god Loucetios, we see the same ancient processes at play. For this reason and given the location of the cult sites of Loucetios and old pagan open air cult sites in the Low Countries, a case can be made for Lôhar being a plausible contemporary Germanic appellation for Loucetios.
There are no literary or epigraphic attestations of the theonym Lôhar. However, many ancient cult sites throughout the Low Countries have the terminal –lo(o) which is derived from the OFrk *Lôh (clearing, meadow, leah). Examples of such are Heiloo (Heilig-lôh) meaning “Holy Wood” and Ermenlo (Irmin-lôh) for “Great Wood or Irmin’s Wood”. The location of two of these important open air cult sites with a historic deposition field from the Late Iron Age to the 13th century are found in Leesten and Herxen, which are along the eastern shore of the lower IJssel. This territory has been identified as one of the birthplaces of the Franks through their founding tribes, such as the Treveri. The toponymical analysis of the name shows a cult sites in Strasbourg, Worms, Eisenburg, to name a few. There is a monument which was erected in Bath (Britain) which identifies Loucetios with Mars and pairs him with the consort Nemetona:
Peregrinus Secundi fil(ius) civis Trever Loucetio Marti et Nemetona
v(otum) s(olvit) l(ibens) m(erito)
Peregrinus, son of Secundus, a Treveran, to Loucetius Mars and Nemetona willingly and deservedly fulfilled his vow.
The Vangiones, an ancient tribe also thought to have been absorbed by the Franks appear by name on a ritually deposited coin in Iron Age Leester.
In TFA, Lôhar may be identified with Tîu, much as how Loucetios is with Mars. Given the mass of depositions of metallic objects, such as pins, coins and medallions at Leester’s hilltop as well as the presence of significant natural fulgurite formations caused by repeated lightning strikes seem to indicate that the open air cult site was important for two factors – lightning and an open clearing. It is the belief of TFA that these hilltops and other open air sites, where the divine lightning bolts meet the sacred earth are indicative of the presence of a “holy (bright) meadows’ god” and that the theonym Lôhar is a fitting appellation for this divinity.
Groenewoudt, Bert. Christianization and the afterlife of pagan open-air cult sites. Evidence from the northern Frankish frontier., p. 15, 2016, Brepols Publisher, Turnhout, Belgium.
 RIB 140