To be fair, militias of the day weren't generally standing militias, and needed to be mustered. We do have definitions as to what militias are informed to us b

To be fair, militias of the day weren't generally standing militias, and needed to be mustered. We do have definitions as to what militias are informed to us by writings of the founders, the federalist papers, previous drafts of the second amendment and, failing that, codified by law in 10 US Code § 311. The definition of militia there ("consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32, under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States and of female citizens of the United States who are members of the National Guard") will likely have been expanded by our recent advances in military equality.