79%RatingSave Gender Masculine Usage Old Irish [1] Pronounced Pron. KA-hə-səkh [key·IPA] Meaning & History Means "vigilant" in Irish. Categories watchful Sources & References O'Brien, Kathleen M. Index of Names in Irish Annals, available from https://medievalscotland.org/kmo/AnnalsIndex/Masculine/Cathassach.shtml.