Final answer:
The official form of address for an archbishop at the end of the 1600s was 'Most Reverend.' This title reflects the hierarchical status of archbishops in the church, particularly in the context of the evolving titles throughout church history.
Step-by-step explanation:
At the end of the 1600s, the official form of address for an archbishop was "Most Reverend." This became a standardized form of address for archbishops within the Christian church. The titling reflects the ecclesiastical hierarchy and respect accorded to high-ranking members of the clergy, like archbishops, who often held significant influence in religious and sometimes temporal affairs.
It is important to understand the context of the term in relation to the history of the Christian church. While the archbishop of Rome, also known as the pope, developed a preeminent position in the Western Church, eventually holding the title of 'pope' which means 'father' of the church, archbishops in other major cities maintained prominent roles within the church hierarchy. Over time, these key religious figures came to be addressed with specific titles that signified their status and position.