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• ad
  ad

  noun

  advertisement.
• ad-
  ad-

  a prefix occurring in loanwords from Latin, where it meant “toward” and indicated direction, tendency, or addition: adjoin . Usually assimilated to the following consonant; see a-, ac-, af-, ag-, al-, an-, ap-, ar-, as-, at-.
• -ad
  -ad

  a suffix occurring in loanwords from Greek denoting a group or unit comprising a certain number, sometimes of years: dyad; triad .
• ad.
  ad.

  abbreviation

  adverb.
• a.d.
  a.d.

  abbreviation

  in the year of the Lord; since Christ was born.
• A.D.
  A.D.

  abbreviation

  active duty.
• AD
  AD

  abbreviation

  anno Domini Compare BC

ad

¹ American  

[ad] / æd /

noun

1. advertisement.

2. advertising.

   an ad agency.

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ad ² American  

[ad] / æd /

noun

Tennis.

1. advantage.

2. ad in, the advantage being scored by the server.

3. ad out, the advantage being scored by the receiver.

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ad ³ American  

[ad] / æd /

preposition

1. (in prescriptions) to; up to.

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ad- ⁴ American  

1. a prefix occurring in loanwords from Latin, where it meant “toward” and indicated direction, tendency, or addition: adjoin . Usually assimilated to the following consonant; see a-, ac-, af-, ag-, al-, an-, ap-, ar-, as-, at-.

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-ad ⁵ American  

1. a suffix occurring in loanwords from Greek denoting a group or unit comprising a certain number, sometimes of years: dyad; triad .

2. a suffix meaning “derived from,” “related to,” “concerned with,” “associated with” (oread ), introduced in loanwords from Greek (Olympiad; oread ), used sporadically in imitation of Greek models, as Dunciad , after Iliad .

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-ad ⁶ American  

1. variant of -ade: ballad .

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-ad ⁷ American  

1. Anatomy, Zoology. a suffix forming adverbs from nouns signifying parts of the body, denoting a direction toward that part: dextrad; dorsad; mediad .

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ad. ⁸ American  

abbreviation

1. adverb.

2. advertisement.

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a.d. ⁹ American  

Or A.D.

abbreviation

1. in the year of the Lord; since Christ was born.

   Charlemagne was born in a.d. 742.

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a.d. ¹⁰ American  

abbreviation

1. before the day.

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a.d. ¹¹ American  

abbreviation

1. after date.

2. autograph document.

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A.D. ¹² American  

abbreviation

1. active duty.

2. anno Domini. Also a.d.

3. art director.

4. assembly district.

5. assistant director.

6. athletic director.

7. average deviation.

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AD ¹ British  

abbreviation

1. anno Domini Compare BC

   70 ad

2. military active duty

3. military air defence

4. Dame of the Order of Australia

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-ad ² British  

suffix

1. a group or unit (having so many parts or members)

   triad

2. an epic poem concerning (the subject indicated by the stem)

   Dunciad

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ad- ³ British  

prefix

1. to; towards

   adsorb

   adverb

2. near; next to

   adrenal

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-ad ⁴ British  

suffix

1. denoting direction towards a specified part in anatomical descriptions

   cephalad

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ad ⁵ British  

/ æd /

noun

1. short for advertisement

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ad ⁶ British  

/ æd /

noun

1. Brit equivalent: van.  short for advantage

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ad ⁷ British  

abbreviation

1. Andorra

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Usage

Because anno Domini means “in the year of the Lord,” its abbreviation a.d. was originally placed before rather than after a date: The Roman conquest of Britain began in a.d. 43 (or began a.d. 43). In edited writing, it is still usually placed before the date. But, by analogy with the position of b.c. “before Christ,” which always appears after a date ( Caesar was assassinated in 44 b.c. ), a.d. is also frequently found after the date in all types of writing, including historical works: The Roman emperor Claudius I lived from 10 b.c. to 54 a.d. Despite its literal meaning, a.d. is also used to designate centuries, being placed after the specified century: the second century a.d.

In strict usage, _ad is only employed with specific years: he died in 1621 ad , but he died in the 17th century (and not the 17th century ad ). Formerly the practice was to write _ad preceding the date ( ad 1621 ), and it is also strictly correct to omit in when _ad is used, since this is already contained in the meaning of the Latin anno Domini (in the year of Our Lord), but this is no longer general practice. _bc is used with both specific dates and indications of the period: Heraclitus was born about 540 bc ; the battle took place in the 4th century bc

Etymology

Origin of ad¹

First recorded in 1795–1800; by shortening

Origin of ad²

First recorded in 1915–20; by shortening

Origin of ad³

From Latin

Origin of ad-⁴

< Latin ad, ad- (preposition and prefix) to, toward, at, about; cognate with at ¹

Origin of -ad⁵

Greek -ad- (stem of -as ), specialization of feminine adjective-forming suffix, often used substantively

Origin of -ad⁷

From the Latin word ad toward, anomalously suffixed to the noun; introduced as a suffix by Scottish anatomist John Barclay (1758–1826) in 1803

Origin of a.d.⁹

From Latin annō Dominī

Origin of a.d.¹⁰

From Latin ante diem

Explanation

An ad is a commercial or a print promotion for some product or service. In other words, an ad is an advertisement. When a company uses print or broadcasting — newspapers, magazines, the Internet, or television, for example — to attempt to sell more of something, it's an ad. Though the word ad is an informal shortened form of advertisement, it's become more commonly used than the original. Those in the business of advertising have objected to this slang form ever since it was first used, around 1840.

Example Sentences

“In the 14th century A.D., a Moroccan explorer named Ibn Battuta documented that a buttery variation of khichuri was eaten daily in South Asia,” wrote Rachael Grow for Mashed.

From Salon • Jun. 7, 2026

To say that our picture of the Mayan civilization—an interlocking network of kingdoms occupying the Yucatán Peninsula and swaths of present-day Guatemala, Belize, Honduras and El Salvador from roughly 1000 B.C. to A.D.

From The Wall Street Journal • Mar. 20, 2026

One of the more remarkable findings was the product of pure scholarship: Mr. Goddio remembered a fresco he’d seen unearthed in Herculaneum, the city buried along with Pompeii by the Vesuvian eruption of A.D.

From The Wall Street Journal • Oct. 14, 2025

He played Georgio, the waiter in the crumbling hotel, in Carry On Abroad in 1972, and also killed daleks and cybermen in the 1966 Dr Who movie Daleks' Invasion Earth: 2150 A.D.

From BBC • Aug. 10, 2025

Two late writers, Apuleius, a Latin, and Lucian, a Greek, both of the second century A.D., make an important contribution.

From "Mythology: Timeless Tales of Gods and Heroes" by Edith Hamilton