Theonym LUGUS

I am sorry! I have NO experience with forums and I do not know how
these work. Suddenly I sow my incoming tray FULL! I said then to me:
oh, what's wrong here?

I would make only a question. What is the most probable PIE-stem for
the celtic theonym LUGUS?

Thank you in advance for it! Can anyone write in the subject "LUGUS"
or something so I can identify the answer?

[To simplify matters I've changed the subject of your post. -BMS]