From Middle French fratricide or its etymon Latin frātricīdium.

fratricide

1. The killing of one's brother (or sister).
2. (military, by extension) The intentional or unintentional killing of a comrade in arms.
3. (military, by extension) The undesirable situation where the separate missiles from a MIRV interfere with each other as they explode.

• (murder) homicide
• (murder of father) patricide
• (murder of king) regicide
• (murder of sister) sororicide

• French: fratricide
• German: Brudermord (of a brother), Geschwistermord (of a sibling), Geschwistertötung (of a sibling), Fratrizid
• Italian: fratricidio
• Portuguese: fratricídio
• Russian: братоуби́йство
• Spanish: fratricidio

From Middle English fratricide, from Middle French fratricide or its etymon Latin frātricīda.

fratricide (plural fratricides)

1. A person who commits fratricide.
   • 1853, John Ruskin, “Roman Renaissance”, in The Stones of Venice, volume III (The Fall), London: Smith, Elder, and Co., […], →OCLC ↗, § LVI, page 73 ↗:

     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.

• brother-slayer

• French: fratricide
• German: Brudermörder, Brudermörderin, Geschwistermörder (of a sibling), Geschwistermörderin (of a sibling)
• Italian: fratricida
• Portuguese: fratricida
• Russian: братоуби́йца
• Spanish: fratricida