Fratricidal is an adjective that describes an act of killing one's brother. It can also be used metaphorically to describe any action that harms someone who is like a brother, such as a fellow soldier or a colleague. Other words that can be used instead of fratricidal include brother-killing, sibling-slaying, and kin-butchery. However, these words are not widely used and may sound archaic or overly dramatic. Other synonyms for fratricidal that are commonly used in contemporary writing include divisive, hostile, and destructive. These words are used to describe actions that cause harm or division among people who are closely related to each other or who share a common bond.