What do the words ‘well regulated militia’ mean to you?

Still-alive
From the text of the 2nd amendment in the us bill of rights.

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”
What do the words ‘well regulated militia’ mean to you?
What do the words ‘well regulated militia’ mean to you?
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