The Meaning of AD: What It Is and How To Use It

The word, acronym, and abbreviation ad all have different meanings. But what is the true meaning of AD? Read more to learn today!

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Ad can be used as a word, an abbreviation, or an acronym. So, how do you know which way a person is using it? This article will cover the various meanings of the word ad and how it can be used.

What Does AD Stand For?

The Latin AD: The Meaning of the Latin Anno Domini

According to Live Science, the term AD stands for the Latin phrase anno domini. This Latin term means, “in the year of our Lord” and labels years that come after the birth of Jesus Christ. People sometimes mistakenly believe that the term AD stands for after death, but this is incorrect. This system of labeling is used by Christians on Gregorian calendars and was invented by Dionysius Exiguus to label the years in his famous Easter table.

To refer to years that came before the birth of Jesus Christ, people use the term BC. This translation is much easier to understand, as it simply means, “before Christ.” People also use the terms BCE and CE to refer to the labeling of the years. These are used as indications of the period of time “before common era” or “common era,” respectively. 

This term is often used to refer to specific years and specific dates, but it can also designate centuries. For example, the second century after the supposed year of the birth of Christ would be labeled as AD2, following AD1 and preceding AD3. The seventeenth century after Christ’s birth would be AD17, or the 17th century AD.

The Prefix Ad-

The prefix ad- has a specific meaning, just like the prefixes ac-, al-, ap-, and af-. This Latin prefix comes from Greek, means toward. It can be used to prefix a preposition or adverb, according to Dictionary. It can also be a suffix to refer to parts of the body and in words like dyad or triad.

The Word Ad

The word ad is also often used as an abbreviation for advertisement or advertising. Many different things can be considered ads, from video ads like commercials to posters. Ads can advertise many things, such as movies, products, and more by a broadcaster or company.

What Are Other Meanings of AD? 

According to The Free Dictionary, AD can stand for more than anno domini. Look at all of the various meanings of AD in the below fields to learn more.

Meanings of AD in Science

If you work in science or STEM, the acronym AD could have any of these definitions:

  • Akabane Disease
  • Automatic Depressurization
  • Animal Development (genetics)
  • Addison’s Disease
  • Adaptive Development
  • Adjoint (mathematics; group theory)
  • Automatic Differentiation
  • Alzheimer’s Disease
  • Acoustic Densitometry (ultrasound)
  • Absolute Deviation
  • Acquisition Doppler
  • Anti-Diarrheal
  • Areal Density
  • Autosomal Dominant (genetics; dominant gene on one of the 23 pairs of autosomes)
  • Atmospheric Deposition
  • Accumulator Dehydrator (automotive A/C component)
  • Anderson-Darling Statistical Test
  • Acoustic Deficiency
  • Advanced Design
  • Auxiliary Drain
  • Adaptive Control (welding)
  • Average Deviation
  • Alternating Direct
  • Alcohol Dependence
  • Asperger’s Disorder

Meanings of AD in Technology

For those of us on the tech side of STEM, ask if AD means one of the following:

  • Active Directory
  • Aperture Door
  • Accastillage Diffusion (French: Distribution Fitting)
  • Activity Discard (ITU-T)
  • Allocation Descriptor (OSTA universal disk format)
  • Application Developer
  • Analog Devices, Inc.
  • Affiliate Defined
  • Alarm Data (Alcatel)
  • Administrative Distance (routing information source rating)
  • Altium Designer
  • Awaiting Disconnection
  • Autonomous Domain
  • Application Development (IBM)
  • Add Delegations (security permissions)
  • Assembly Drawings (Nortel)
  • Assignment Date
  • Affinity Diagram (Sprint – Quality)
  • Address Data
  • Access Denied
  • Activation/Deactivation

Meanings of AD in Business

For all of the businessepeople trying to decode AD, let this list be your guide:

  • Addendum Document (to an OSI Standard; ISO)
  • Archival Disc (disc storage)
  • Accumulated Depreciation (accounting)
  • Audio Description (cinema accessibility)
  • Accrued Depreciation (finance)
  • Attila Dogan Company
  • Associate Director
  • Advertisement
  • Approved Document (UK)
  • Agency Development (various organizations)
  • Annuity Due
  • Amministratore Delegato (Italian management designation)
  • Addendum

Meanings of AD in Government

Government officials may know these common meanings for AD:

  • Assistant Director
  • Air Defense
  • Aid to the Disabled
  • Antidumping Duty
  • Advance Development
  • Airworthiness Directive
  • After Deployment
  • Armored Division
  • Auxiliary Destroyer Tender
  • Air Directive
  • Acquisition Directorate
  • Active Duty
  • Advanced Deployability
  • Approved Direction
  • Army Depot
  • Airdrop
  • Admiral
  • Administratively Determined
  • Advanced Development
  • Area Defense
  • Attack Director
  • Alliance for Democracy (Nigeria)
  • Automatic Distribution (US DoD)
  • Priority Add-On (US DoD)
  • Aviation Division
  • Alternativa Demokratika/Alliance for Social Justice (Malta)
  • Accession Document
  • Associated Document

Meanings of AD as Slang Terms

We use slang terms every day, but we don’t always know what they mean. Have you been using these definitions of AD?

  • Alexis Denisof (actor)
  • An der Donau (German:on the Danube)
  • Antonio Davis
  • Artificial Dumbness
  • Attention Danger (gaming clan)
  • Adellion (game)
  • After Dianetics (L. Ron Hubbard)
  • American Dad (TV show)
  • Anaheim Ducks (hockey)
  • Arrested Development (rap group)
  • American Dream
  • Autograph Document
  • Arrested Development (TV show)
  • Albus Dumbledore (Harry Potter)
  • Academic Decathlon
  • Academic Don
  • Ace Deuce (band)
  • Azumanga Daioh (anime)
  • Adopted Daughter
  • Aberforth Dumbledore (Harry Potter character)
  • Alien Dice (webcomic)
  • Azure Dreams (role-playing game)
  • Audio Drama
  • Adrian Peterson (Oklahoma Sooners football player)


If you see the term AD after a date or year, it will most likely stand for the Latin anno domini in general practice, but others use BCE and CE with strict usage. This is one of many Latin loanwords used in English. Ad can also be a prefix or stem of a word like sp- or sc-.


  1. AD – What does AD stand for? | The Free Dictionary 
  2. Keeping time: The origin of B.C. and A.D. | Live Science 
  3. Ad- Prefix |