Learn how to say Ad correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word AD:
Anno Domini (used to indicate that a date comes the specified number of years after the traditional date of Christ’s birth).
ad is normally written in small capitals and should be placed before the numerals, as in ad 375 (not 375 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 (not ad the third century). Compare with BC.