Definition of AD in English:

AD

  • 1Military
    Active duty.

  • 2Anno Domini (used to indicate that a date comes the specified number of years after the accepted date of Christ's birth)

  • 3Armored division.

  • 4Athletic director.

Usage

In dates, AD is normally written in small capitals and is traditionally placed before the numerals, as in AD 375 (not375 AD). The reason for this is that AD is an abbreviation of anno domini, which means ‘in the year of our Lord.’ However, when the date is spelled out, it is normal to write the third century AD (notAD the third century). Compare with BC. In recent years, some writers have begun using the abbreviations CE (of the Common Era) in place of AD, and BCE (before the Common Era) in place of BC, in consideration of a more secular and international readership