Learner's definition of ARMOR
special clothing that people wear to protect their bodies from weapons
◊ Armor commonly refers to the heavy metal suits that men wore long ago when they fought in battles.
see also knight in shining armor at 1knight
◊ A chink/crack in someone's or something's armor is a weakness that might cause someone or something to fail or to be defeated.
They watched carefully for any cracks in the other team's armor.
The plan looks good, but we've found/discovered some chinks in its armor.
The scandal revealed/exposed a chink in his seemingly perfect armor.
a hard covering that protects something (such as a vehicle or an animal)
The shots penetrated/pierced the tank's armor.
an armor-plated vehicle [=a vehicle that is protected by armor; a vehicle that is covered in flat pieces of metal]
The armadillo's armor consists of a series of small, bony plates.
— often used before another noun
soldiers and vehicles (such as tanks) that are protected with armor