something used instead of a person's realname that either makes it shorter, is a joke, or is a word that describes their personality

1. Blue Monday is the most depressing day of the year, calculated by Dr. Cliff Arnall, a researcher at the University of Cardiff's Center for Lifelong Learning.
Factors used to calculate the date included weather conditions, debt level, time since Christmas, time since failing our New Year's resolutions, low motivation and feeling the need to take action.

In 2005 the date was calculated as January 24th, in 2006 it was January 23rd, and in 2007 it was January 22nd.

2. A song by the hard rock band Orgy from their album Candy Ass.

A name given to a person that is typically a shorter version of their existing full name. Nicknames can also be given to a person based on personality traits or other defining attributes of that person. The "nickname" usually derives from a friend, family member, or sometimes enemy calling a specific person a name not their own. The "nickname," if catchy enough, will stick and that person will begin being referred to by their nickname moreso than their actual full name.

The term, "nickname" originated from the the time of St. Nicholas when people had a particular difficulty with phonetics. The commoners had difficulty saying Nicholas, so they began calling him: "St. Nick", The term, "nick" also referrs to something being chipped off, such as: "Thou nicked off a piece of thine rock to make it fit in thy dwelling." Over the centuries, nickname became the term for a shortening of someone's full name, like a part of it being nicked off.

A nickname is a term of familiarity between a person or a thing/another person.

A name used to represent you or make fun of you.

A name that someone gives you because they don't like your real name

A Name One Prefers