Fratricide

[Dave Paprocki]

The act of one who murders or kills his own brother.

[Tina]

N
1: a person who [murders] their brother or sister
2: the act of murdering your own brother or sister
3: fire that injures or kills an ally, or fellow [countryman], commonly referred to as [friendly fire]

[Gregory]

Fratricide is when [you kill] your own brother.

Fratricide is when you kill a brother in arms (soldier or political/[religous] brother) who you are fighting with either [on purpose] or by accident.

[Ernesto]

The killing of ones brother or sister.

[Hina Muqadas]

That one Steam award you get when you kill the [companion cube] in Portal. You know, the one that made [MatPat] from [Game Theory] make a video about how the cubes have dead bodies in them.
(also, the actual definition is killing your brother/sister)

[Tina]

the crime of murdering your brother, or killing members of your own group or country