What is a ship?

A ship is a large vessel that floats on water. They serve a lot of purposes - they can fish, serve in warfare, be around just for the helluva it, etc. But you better watch out if you have a ship, because it might be commandeered by Jack Sparrow.

Or, ship is a fictional couple that a fan wants to get together, or is together. It's just a pairing that they love.
Ship could also be used as a verb, though. Like: I ship Huddy!

It's a pie that floats on water.

Oh don't worry, When I was new last year, I too asked the same question!!! It's what r-pattz just said ^

a ship is a couple...

Ship means two things. First. it's what r-pattz said. And if you're talking about TV or movies, it's a couple or a character that you prefer. Like if I say I ship Damon and Elena in The Vampire Diaries, or Ron and Hermione in Harry Potter, this means I like Damon and Elena and Ron and Hermione. If I say I ship Katherine Pierce or Hermione Granger. It means Katherine Pierce and Hermioen Granger are my favorite characters. Hope I helped.