What Latin term means "from the beginning"?

The Latin term "Ab initio" translates directly to "from the beginning." This phrase is commonly used in legal and scientific contexts to refer to situations, decisions, or conditions that are considered from their origin or starting point. For example, in legal cases, it might denote that a situation or contract is valid from the very start, rather than taking into account later developments or changes.

In contrast, the other terms have distinct meanings: "Ad vitam aeternam" refers to something that lasts for eternity or for an indefinite time; "Quid pro quo" means a favor or advantage granted in return for something; and "In situ" indicates something that is in its original place or position. Understanding these differences can help clarify why "Ab initio" is the term that specifically denotes the concept of origin or beginning.