Where does “Dublin” come from?

Dublin derives from Old Irish Duibhlinn, from Old Irish dubh meaning "dark" and linn meaning "pool," referring to a dark body of water.

Ancestry of “Dublin”, step by step

Step	Language	Word	Meaning
1	Old Irish	dub	black; morally dark, dire, gloomy, melancholy;...
2	Proto-Celtic	dubus	black
3	Proto-Indo-European	dʰewbʰ-	deep
4	Proto-Indo-European	dʰewh₂-	smoke; mist, haze

Dublin — Etymology, Origin & Word History | Etymology Explorer