[ 'fratrɪsʌɪd ]
■ noun
1》 the killing of one's brother or sister.
↘a person who does this.
2》 the accidental killing of one's own forces in war.
Derivatives
fratricidal adjective
Origin
C15: via Fr. from late L. fratricidium , from frater 'brother' + -cidium (see -cide ).