Where does “Antrim” come from?

Antrim (Portuguese) comes from English Antrim, from Irish Aontroim, from Old Irish óen, from Proto-Celtic oinos, from Proto-Indo-European óynos — one; single.

Ancestry of “Antrim”, step by step

StepLanguageWordMeaning
1EnglishAntrimthat is the county town
2IrishAontroimlone ridge
3Old Irishóenone
4Proto-Celticoinosone
5Proto-Indo-Europeanóynosone; single
Every word from Proto-Indo-European óynos →Every word from Proto-Celtic oinos →Every word from Old Irish óen →