An Epithet (from Ancient Greek ἐπίθετον (epítheton) ‘adjective’, from ἐπίθετος (epíthetos) ‘additional’), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleiman the Magnificent, Richard the Lionheart, and Ladislaus the Short, or allusive, as in Edward the Confessor, William the Conqueror, Æthelred the Unready, John Lackland, Mehmed the Conqueror and Bloody Mary.

The word epithet also may refer to an abusive, defamatory, or derogatory word or phrase. This use is criticized by Martin Manser and other proponents of linguistic prescription. H. W. Fowler noted in 1926 that “epithet is suffering a vulgarization that is giving it an abusive imputation”.

wikipedia/en/Epithet

Fratricide (from Latin fratricidium; from frater ‘brother’ and -cīdium ‘killing’ – the assimilated root of caedere ‘to kill, cut down’) is the act of killing one’s own brother.

It can either be done directly or via the use of either a hired or an indoctrinated intermediary (an assassin). The victim need not be the perpetrator’s biological brother. In a military context, fratricide refers to a service member killing a comrade.

The term is often used metaphorically to refer to civil wars.

wikipedia/en/Fratricide