Speaking of words and phrases that, over time, are self-adaptive, i.e., their popular definition undergoes alteration to reflect changing moral attitudes, e.g., "Manifest Destiny" - causes me to wonder how in the minds of many, certain other words, phrases are not subject to change other than by written Amendment, e.g., The US Constitution, the DoI.

Could it be that undefined (unwritten) terms are subject to change while unwritten words, phrases are not subject to change and that is the reason that at the time of their origin, they were purposefully left unwritten in order to permit future change to fit future circumstances?

Another way of saying that is to say that may be the reason "Manifest Destiny" never made it into the hallowed halls of the U.S. Congress for the purpose of recording its meaning in a final, agreed to form. Likewise with the word "Rebellion" which, although it appears in the U.S. Constitution, is nowhere else (that I am aware of) defined by the framers within a Constitutional context?