Where does “cathais” come from?

cathais (Irish) comes from Old Irish cath, from Primitive Irish ᚉᚐᚈᚈᚒ, from Proto-Celtic katus, from Proto-Indo-European kéh₃tus, from Proto-Indo-European -tus — Derives action nouns from verb roots.

cathais (Irish): vigil, watch

Definitions

  1. vigil, watch

Ancestry of “cathais”, step by step

cathais traces back through two separate lines of ancestry.

via Old Irish cath

StepLanguageWordMeaning
1Old Irishcathbattle, fight; troop, battalion
2Primitive Irishᚉᚐᚈᚈᚒbattle
3Proto-Celtickatusbattle
4Proto-Indo-Europeankéh₃tusfight
5Proto-Indo-European-tusDerives action nouns from verb roots

via Old Irish fess

StepLanguageWordMeaning
1Old Irishfesspassive singular perfect prototonic of...
2Proto-Celticwissosknown
3Proto-Indo-Europeanwidtósseen; known
4Proto-Indo-Europeanweyd-to see
Every word from Proto-Indo-European -tus →Every word from Proto-Indo-European kéh₃tus →Every word from Proto-Celtic katus →