What's a tender Port?

Sometimes I forget how scary my first cruise was, looking at all the different itineraries available, all the different cruise lines, all the ships and the almost indecipherable jargon that people used.
Port?
Starboard?
OBC?
Guaranteed cabins?
Inside/outside/balconies?
and tender ports!
I was talking to a first time cruiser yesterday and she mentioned her son was disabled, so, looking for a suitable itinerary I told her we'd have to watch out for tender ports.
She didn't have a clue what I was talking about, which I could understand when I came to think about it. If you've never heard the term before it can be quite confusing.
So, what's a tender port?

First, Second and Freedom Dining on a cruise ship – Explained

I’ve been surprised this week by the amount of cruisers who were still confused about freedom dining. This is still a fairly new option in cruising terms but is getting more and more popular, but is it as good as it seems or are the other two options better for some people? Today I’m going to be talking a little about the different dining options available on cruise ships with their associated pros and cons.