ᚉᚒᚂᚔᚇᚑᚃᚔ

Meaning: “gnat, fly” + “black”

From Proto-Celtic *kulis (“gnat, fly”) + *dubus (“black”). Matasović suggests a reconstruction *Kūlidubwī since the development *-bw- to -v- is regular in Primitive Irish. The long ū in that suggestion also implies that the first element is *kūlos (“corner, backside”), but a derivation from *kulis better explains why the linking vowel is -i- rather than -o- or -a-.