flechette

noun, plural flé·chettes [fley-shets; French fley-shet] /fleɪˈʃɛts; French fleɪˈʃɛt/.

1. Military. a small, dartlike metal projectile used as shrapnel in antipersonnel bombs and shells.
2. a bullet with a thin, hard metal spine, designed to tumble on impact and thus cause an incapacitating wound.

noun

1. a steel dart or missile dropped from an aircraft, as in World War I