The suits of armour must always have some level of magic about them, since they were referred to as "creaking" along with the muttering portraits when Harry and Ron arrived at Hogwarts for their second year (CS5)
At Christmas time mysterious lights (everlasting candles, evidently) shine from inside every suit of armour in the castle (PA11, HBP15). During some years they are bewitched to sing Christmas carols as well (GF22).
A nearby suit of armour once laughed at Neville when he tripped on the stairs (GF12).
When Harry hid behind a suit of armour in the corridor outside Umbridge's office, the helmet turned to watch him (OP29).
McGonagall used Piertotum Locomotor to animate the suits of armour, sending them into the battle of Hogwarts (DH30).
The word "armour" was introduced into use in the Middle Ages as a borrowing from the French. It is dated from 1297, as a "mail, defensive covering worn in combat" from Old French armoire, itself derived from the Latin armatura "arms and/or equipment" with
Armour (spelt armor in the United States of America) is a protective covering that is used to prevent damage from being inflicted to an object, individual, or vehicle by direct contact weapons or projectiles, usually during combat, or from damage caused by a potentially dangerous environment or action (e.g., cycling, construction sites, etc.). Personal armour is used to protect soldiers and war animals. Vehicle armour is used on warships and armoured fighting vehicles.