nickname
nick-name
verb
To give someone or something an informal, descriptive, or affectionate name.
"They nicknamed her 'Tiny' despite her height."
noun
An informal, often descriptive or affectionate name given instead of a person's real name.
"His nickname 'Spud' suited him perfectly."
Thesaurus
Synonyms: soubriquet, sobriquet, cognomen, moniker, byname, dub