Harbour, landing place, bank. Written Port — the same Irish word, port, in the spellings English gave it.
Harbour, landing place, bank: it is the Irish port. It is written Port in English spellings of Irish names.
port. English spellings of the same word include Port, because the names were written down by ear.
Portlaoise (Port Laoise), Westport (Cathair na Mart), Portadown (Port an Dúnáin), Portarlington (Cúil an tSúdaire).