Where does “Cillian” come from?

Cillian (Irish) comes from Irish ceallach, from Irish -ach, from Middle Irish -ach, from Old Irish -ach, from Proto-Celtic -ākos, from Proto-Indo-European -eh₂ḱos, from Proto-Indo-European -kos — Creates deadjectival and desubstantival...

Ancestry of “Cillian”, step by step

Cillian traces back through two separate lines of ancestry.

via Irish ceallach

StepLanguageWordMeaning
1Irishceallachrecluse, hermit; celled, cellular
2Irish-achForms nouns from other nouns and adjectives with...
3Middle Irish-achForms adjectives meaning "related to, having,...
4Old Irish-achForms adjectives meaning "related to, having,...
5Proto-Celtic-ākosForms adjectives from nouns and adjectives with...
6Proto-Indo-European-eh₂ḱos
7Proto-Indo-European-kosCreates deadjectival and desubstantival...

via Irish ceall

StepLanguageWordMeaning
1Irishceallgenitive plural of cill; monastery, church

Words derived from “Cillian

Every word from Proto-Indo-European -kosEvery word from Irish -achEvery word from Old Irish -ach