Question: The coming of the millennium got me thinking about the use of the abbreviations "A.D." and "B.C." I know that one is an abbreviation for an English term and one is an abbreviation for a Latin term. Why is that? I've also seen "C.E." used for dates -- what is that an abbreviation for?Answer: It is indeed odd that we use an English abbreviation for dates before the birth of Christ and a Latin one for dates after. Probably for this reason, "A.D." is sometimes explained as standing for "after death." But you're right; in origin it is truly Latin, standing for "Anno Domini," which means "in the year of the Lord."
For most general purposes, one is interested in current and recent dates. The abbreviation "A.D." was introduced in opposition to other systems for reckoning these dates, rather than as a specific contrast to the pre-Christian period. Thus "A.D." can be contrasted with "A.U.C.," a Latin abbreviation for "ab urbe condita," which reckoned dates from the foundation of Rome. You will also sometimes see the Latin abbreviation "A.H.," for "anno Hegirae," which refers to dates as figured by Muslims and takes the Hegira, Muhammad's flight from Mecca to Medina, as its starting point. Another is "A.L.," which stands for "anno lucis," meaning "in the year of light." This system takes 4000 B.C. as the starting point and is sometimes used by Freemasons.
"C.E." is synonymous with "A.D." It stands for "Common Era" or "Christian Era," and is especially favored by those who prefer to avoid the religious implications of "A.D."