Real Dictionary

-ad in American English 1
the name of any of certain collective numerals
suffix: a suffix occurring in loanwords from Greek denoting a group or unit comprising a certain number, sometimes of years

-ad in American English 2
toward, in the direction of
suffix

-ad in American English 3
suffix: a suffix forming adverbs from nouns signifying parts of the body, denoting a direction toward that part

-ad in British English 1
suffix forming nouns: a group or unit (having so many parts or members)

-ad in British English 2
suffix forming adverbs: denoting direction towards a specified part in anatomical descriptions

a.d. in American English
abbreviation: active duty
abbreviation: after date

ad
You use AD in dates to indicate the number of years or centuries that have passed since the year in which Jesus Christ is believed to have been born. Compare BC.
countable noun: An ad is an advertisement.

AD in American English
active duty

ad in American English 1
noun: an advertisement

ad in American English 2
advantage (sense 4)
noun

ad in American English 3
up to; so as to make
preposition: to; up to

AD in British English
abbreviation for: anno Domini

ad in British English 1
noun

ad in British English 2
noun

ad in British English 3
the internet domain name for: Andorra

ad- in American English
motion toward, addition to, nearness to
prefix: a prefix occurring in loanwords from Latin, where it meant “toward” and indicated direction, tendency, or addition (adjoin)

ad- in British English
prefix: to; towards

ad. in American English
abbreviation: adverb