→"Supersession" as a simple concept
"Supersession" comes from the word "supersede", which means “to set above; to make void or inoperative by a superior authority; to stay, suspend or supplant” <ref> Kendrick Kinney: A Law Dictionary and Glossary, 1893, Callaghan and Company, p. 642</ref> It can also mean to overrule, override, or replace the function of something.
For example, an amendment to a law supersedes the original law, a governor's pardon overrules a sentence prescribed by law, and a remodeled home or car replaces the old one. Note that in each of these cases that which is superseded may remain in existence or operation fully or partially. Consequently, supersession may cause the new thing to remove, modify, affect or only add to the previous one.
==="Supersession" in Orthodoxy===