徹てっ甲こうMeanings1noun, used as a prefixarmor-piercingTechnical prefix used in military and ordnance contexts, such as 徹甲弾 (armor-piercing shell) or 徹甲榴弾 (armor-piercing high-explosive shell). Not used as a standalone noun.徹てっ甲こう弾だんは戦せん車しゃの装そう甲こうを貫つらぬくために設せっ計けいされている。Armor-piercing shells are designed to penetrate tank armor.