Referring to devices (typically munitions) intended to pierce armor(adjective)
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Use "armor-piercing" in a sentence
"Luckett was a young platoon leader on his first tour in Iraq when an explosively formed penetrator – a bomb that hurls an armor-piercing lump of molten copper – ripped through his vehicle on a Baghdad street on Mother's Day 2008."
"It can also be used to produce high-explosive weapons, such as armor-piercing rockets."
"He also possessed armor-piercing ammunition, saying it was “to attack Americans,” and said that one of his weapons would be used “for the base,” an apparent reference to the Quantico facility."