Shield
It depends on what shield you are referring to . Shield could mean a firewall or an antivirus like mcafee
"On [a/the] shield."
they mean power
to guard
green bean
If you mean the design of the shield, it was updated with the times. The early armies used roundish or oval shields, then changed to the rectangular shield, which in turn gave way to the rectangular curved shield. With this curved shield a man could step into his shield to use it for pushing and it also protected his sides to an extent. If you mean any design on the outside of the shield, it was the emblem of the legion, if it was there at all. Most Roman shields are believed to have been unadorned, despite what Hollywood tells you.
=== === There are several shield volcanoes around the world. You could mean any of them
Aegis was the Greek word for "shield". The AEGIS system is a system that is designed to shield the ship.
i mean shield
'Canadian shield'
War symbol