cognominate

Example:He was known as 'The Phantom' by his teammates, a cognominate that referred to his elusive and silent playing style.

Definition:A familiar or informal name used instead of a person's usual name, often chosen for a particular characteristic.

Example:The children loved to call their woolly dog 'Fuzzy' because of the way his fur looked up close.

Definition:To give someone or something a name, especially an informal one.