A nickname or nick, also known as a sobriquet, is a substitute for the proper name of a person, place or thing. It is commonly used to express affection, amusement, a character trait or defamation of character. It is distinct from a pseudonym, stage name or title, although the concepts can overlap. Nicknames are typically informal.

A pseudonym or alias is a fictitious name that a person assumes for a particular purpose, which differs from their original or true name (orthonym). This also differs from a new name that entirely or legally replaces an individual's own. Many pseudonym holders use them because they wish to remain anonymous, but anonymity is difficult to achieve and often fraught with legal issues.