A generic term describing a garment worn into battle or hazardous environment.
The earliest battle armor known to man were made of skins and leather. evolved to the Steel armor medeival knights wore and into the Kevlar and ballistic protection of 21 century warriors.
In the 54th century it could mean a wide array of suits and suit systems. Union military generally uses battle suits or battle armor that is also deep space worthy and can act as a space suit.