Nickname n. : A name given in contempt, derision, or sportive familiarity; a familiar or an opprobrious appellation.

Nickname v. t. : To give a nickname to; to call by a nickname.

Example:
What is the worst Nickname you can give someone?

Taxonomy
nickname, kin, proper name, Robert, City, real name, free encyclopedia, Athletic nickname, List of military figures by nickname, List of monarchs by nickname, List of sportspeople by nickname, given name, affection, Fountains, slaves, Opa, Articles with unsourced statements, fictional characters.

Defination from the web:
nickname "Jimmy" ... The term hypocoristic is used to refer to a nickname of affection between those in love or with a close emotional bond, compared with a term of endearment. ...