Where does “Lyon” come from?

Lyon comes from French Lyon, derived from Latin Lugdunum, which originated in Gaulish Lugodunon, a place name of uncertain etymology.

Ancestry of “Lyon”, step by step

Step	Language	Word	Meaning
1	French	Lyon	—
2	Latin	Lugdūnum	—
3	Gaulish	Lugudūnon	—
4	Proto-Celtic	Lugus	the god {{w\|Lugus}}