Yes, another multi parter! There’s actually a ton of words that are port related. Way more than I thought. It’s actually going to take three posts for me to get through them all. So let’s start by looking at just plain port, which has so many versions that it’s a whole posts worth itself.
The version of port that means where ships go comes from the Old English port which means…port. Okay, no surprises there. That in turn comes from the classical Latin portus, which also (big shock) means port, and even earlier it was the Proto Indo European prtu-, a passage, and per-, to lead or pass over. And speaking of ships, the left side of one is also called port, probably just to be confusing. Apparently it was named after, and I quote, “the side facing the harbor” when the ship is docked. (-.-) Before the mid-sixteenth century, they used larboard, the opposite of starboard, instead.
The port that means portal also comes from per-, through a similar yet distinct lineage. It also used to be port in Old English, then it was the Old French porte and classical Latin porta, gate. Port also has the definition of carry attached to it, coming from the Middle French porter and classical Latin portrare, to carry. And yeah, that’s related to portus and porta.
The port that’s an alcoholic beverage has a kind of weird relationship to the others. It’s short for Oporto (or Porto), a city in Portugal which shipped the drink. And that Porto comes from port. As does the first part of Portugal. Because this ouroboros just keeps eating itself.
TL;DR: All versions of port started out as the same word, became something different, then became the same word again because language is dumb.
Tony Jebson’s page on the Origins of Old English