Also a nuclear weapons term.

It describes the destruction or neutralization of one nuclear weapon by another belong to the same side, because friendly detonations were too close .

As I recall, this was a major consideration in the deployment of the Peacekeeper missile during the Reagan administration - they were deployed in a single silo field in close proximity to induce fratricide among any Soviet missiles targeting the silos.

Also a term frequently used in place of friendly fire.

Incidents of fratricide occur in all wars. Most can be attributed to the fog of war.

Frat"ri*cide (?), n. [L. fratricidium a brother's murder, fr. fratricida a brother's murderer; frater, fratris, brother + caedere to kill: cf. F. fratricide.]

1.

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

2. [L. fratricida: cf. F. fratricide.]

One who murders or kills his own brother.

© Webster 1913.