Final answer:
The important legal term not included in the original Bill of Rights is 'privacy'. The Ninth Amendment alludes to unnamed rights that are retained by the people, which has been interpreted to include privacy. The first ten Amendments did not settle the powers between federal and state authority.
Step-by-step explanation:
The important legal term not included in any of the original 10 Amendments that make up the Bill of Rights is 'privacy'. The Ninth Amendment allows for unnamed rights to be recognized, and the Supreme Court has held that this includes the right to privacy even though it is not explicitly mentioned in the first eight amendments or the Bill of Rights. It wasn't until later amendments, particularly the 14th Amendment with its clause on 'equal protection under the law', that the concept of privacy would be more solidly interpreted into American constitutional law. Additionally, as we discussed, neither the Bill of Rights nor the first ten amendments settled all the questions about federal versus state authority. This interpretation vastly expanded with the inclusion of the 13th, 14th, and 15th Amendments, which extended civil liberties and began the process of the selective incorporation of the Bill of Rights into state law.