Reactive armor

From Memory Alpha, the free Star Trek reference

Reactive armor is a type of armor that explodes outwards to deflect incoming weapons fire.

The Breen-made CRM 114 was guaranteed to cut through reactive armor in the six to fifteen centimeter range. (DS9: "Business as Usual")

One, an advanced Borg drone with 29th-century technology, was equipped with reactive body armor. (VOY: "Drone")