a metallic sheathing or protective covering, especially metal plates, used on warships, armored vehicles, airplanes, and fortifications. mechanized units of military forces, as armored divisions. Also called armament. any protective covering, as on certain animals, insects, or plants.

Meaning of armour in English strong covering that protects something, especially the body: Police put on body armour before confronting the rioters. In the past, knights used to wear suits of armour (= protective covering made of metal) in battle. These grenades are able to pierce the armour of tanks.

Plank opted to use the British spelling "armour" in the company name because the toll-free vanity number was still available for that version. People began to take notice of the brand when a front-page photo of USA Today featured Oakland Raiders quarterback Jeff George wearing an Under Armour mock turtleneck.

armour, protective clothing with the ability to deflect or absorb the impact of projectiles or other weapons that may be used against its wearer.