This is the 829th most frequent Greek word.
πειραιά
"Pειραιά" (Piraeus): A port city in Greece, part of the Athens urban area, and the chief seaport.
Here, 'Πειραιάς' refers to a specific geographical location, the city and port of Piraeus.
Ο Πειραιάς είναι το μεγαλύτερο λιμάνι της Ελλάδας.
Piraeus is the largest port in Greece.
In this sentence, 'Πειραιά' is in the accusative case, highlighting motion towards the location.
Πήγαμε στον Πειραιά για να πάρουμε το πλοίο για τα νησιά.
We went to Piraeus to take the ship to the islands.
Here, 'Πειραιά' is in the locative context, representing the place where the taverns are.