plate armour pla·tear·mour uncommon noun 1. specially hardened steel plate used to protect fortifications or vehicles from enemy fire Synonymsarmor platearmour platearmor platingplate armorplate armour Related words Broader terms plate Narrower terms backplatebeaverbrassardbreastplatecannonchanfroncubitierecuisse WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.