fratricide

noun

1. (countable, uncountable)The killing of one's brother (or sister).

   “The new accusation brought by Urban against Manfred of murdering his sister-in-law's embassador – it may be observed that, tacitly, he acquits him of parricide, fratricide, and nepoticide – requires a little explanation.”

   “Terms related to familicide include filicide (the killing of one's child or children), uxoricide (the killing of one's wife), fratricide or sororicide (the killing of one's brother or sister), avunculicide (the killing of one's uncle), and nepoticide (the killing of one's nephew).”

2. (broadly, countable, uncountable)The intentional or unintentional killing of a comrade in arms.

   “From January on, Third Army also spent a good deal of energy trying to solve the problem of fratricide, the killing or injuring of one's own forces by what is ironically called 'friendly fire,'[…]”

   “Such a press of arms invites many opportunities for unintentional fratricide.”

3. (broadly, countable, uncountable)The undesirable situation where the separate missiles from a MIRV interfere with each other as they explode.
4. A person who commits fratricide.

   “Can Signorio was twice a fratricide, the last time when he lay upon his death-bed: his tomb bears upon its gables the images of six virtues, — Faith, Hope, Charity, Prudence, and (I believe) Justice and Fortitude.”

   “The conversion of Russia to Christianity was effected, it would seem by a monster of cruelty and lust. That Vladimir (980–1015) was a fratricide, who maintained 3,500 concubines, has not prevented his canonization as a saint.”