noun, masculine/ɔ.by.flɛʃ/plural: obus-flèches
obus-flèche is masculine in French.
kinetic energy penetrator, a non-explosive high-velocity projectile whose destruction power comes from its speed, its density and its hardness
From obus, "artillery shell" and flèche, "arrow", because of its shape (long and thin, pointed, with fins like an arrow)