The term "shipper" comes from supporting a ship. To ship something means a person wants two characters to get together and/or shows support for two characters already together. The term "ship" came from the X-Files fandom, when fanfics were written about Mulder and Scully. The fans then called themselves shippers. It quickly spread and is now the title a person gives themself if they believe two charcters should or will be together (The characters can be from anything: Books, Movies, Television, Video Games, and even Actors/Actresses). It is not limited to the couple actually happening, a person can ship something just because they enjoy the possibility of them getting together or even just because they think they would look good together.

Let me die.

A slang word derived from 'relationships' that generally means people who support certain relationships in fanfiction. It is a common joke to say that you "sail" on a certain ship. Most commonly identified with the Harry Potter fandom.

relationshipper; One who believes there is, was, should, and could be a relationship between 2 characters in a certain fandom.

a person who supports a relationship between two people, real or fictional.

A fan devoted to a paticular couple/pairing in a fandom. Usually fanatical.

Fanfics revolving around a certain relationship.