Ultimogeniture is a term used to describe the inheritance system where the youngest child inherits everything. This system is considered rare and outdated today, and it's important to have alternatives for it. Some synonyms for ultimogeniture include "junior right," "youngest child inheritance," and "cadetship." The term "youngest primogeniture" can also be used to describe inheritance systems where the youngest also inherits, but only if there are no male heirs. Another synonym is "benetficiary system," which is used when the youngest child is given special rights and privileges in the inheritance process. Regardless of which term is used to describe this type of inheritance system, it's important to understand the nuances and implications of each.