Zonguldak Etymology of the name
The city's name probably comes from Zone Geul-Dagh, the name given to the area by French and Belgian mining companies. Göldağı ("Lake Mountain") is the highest mountain in the vicinity of Devrek district.
Following information about Ereğli coal mining history, will help us to understand Zonguldak name is originated from Zone Geul-Dagh in French: (In Catholic Encyclopedia, with reference of year 1908, Zonguldak town is called as "Zoungoul-Dagh" or in Turkish, Zoungoul mountain; or with Turkish+French meaning, Lake/Göl mountain zone "Goul-Dagh is a mountain on the south of Zonguldak town, with a little lake It was a reference benchmark for the new mining zone and sea port location in Eregli region after 1860s.")
Another etymology is that the name originates from the Turkish zongalık or zongura or it may have arisen from the name of the nearby ancient settlement of Sandraka or Sandrake.
According to another theory the name may have come from a compound word, namely Jungle-Dagh, from jungle which the French entrepreneurs named due to uneven and wooded geography of the land, and dağ meaning "a mountain" in Turkish.