AD
Abbreviation with 15 meanings
| Stands for | Anno Domini (in the year of the Lord) |
|---|---|
| Meanings | 15 |
| Categories | Religion, Writing & Everyday, Medical, Technology & Computing, Military, Geography & Places, Science & Engineering, Business & Finance, Texting & Internet Slang, Arts & Entertainment |
| Also written | A.D., ad |
AD has 15 meanings. The most common are Anno Domini (in the year of the Lord) (religious term) and Advertisement (everyday); it can also stand for Atopic dermatitis, Advance directive, Alzheimer's disease, Assistive device and Active Directory, plus 8 more listed below.
Meanings of AD at a glance
| # | AD stands for | Context |
|---|---|---|
| 1 | Anno Domini (in the year of the Lord) | Religion › Religious Term |
| 2 | Advertisement | Writing & Everyday › Everyday |
| 3 | Atopic dermatitis | Medical › Dermatology |
| 4 | Advance directive | Medical › Emergency Medicine |
| 5 | Alzheimer's disease | Medical › Neurology |
| 6 | Assistive device | Medical › Rehabilitation |
| 7 | Active Directory | Technology & Computing › Computer |
| 8 | Active duty | Military › Military Term |
| 9 | Andorra | Geography & Places › Country Code |
| 10 | Autosomal dominant | Science & Engineering › Genetics |
| 11 | Aggregate demand | Business & Finance › Economics |
| 12 | Attack damage | Texting & Internet Slang › Gaming Slang |
| 13 | Aviation Machinist's Mate | Military › US Navy and Coast Guard Rating |
| 14 | Assistant director | Arts & Entertainment › Film, Television and Theater |
| 15 | Auris dextra (right ear) | Medical › Medication Route |
1. Anno Domini (in the year of the Lord)
Religion · Religious Term Abbreviations · also used in measurement and general use
Label for years counted from the traditional year of Jesus' birth in the Western calendar, as in AD 1066. The system was devised in 525 by the monk Dionysius Exiguus for calculating Easter and spread through the writings of the English historian Bede in the 8th century.
Example: The Western Roman Empire is traditionally said to have fallen in AD 476.
By tradition AD goes before the year (AD 70) but after a century (the fourth century AD); AP style writes A.D. with periods, while Chicago now prefers AD, often in small capitals. There is no year zero: 1 BC is followed directly by AD 1. Most historians believe Jesus was actually born between about 6 and 4 BC, since Herod the Great died around 4 BC. CE is the religiously neutral equivalent.
2. Advertisement (ad)
Writing & Everyday · Everyday Abbreviations
Clipped form of "advertisement," meaning a paid announcement promoting a product, service, event or cause in print, broadcast, online or outdoor media. It is the everyday word in speech, marketing and journalism.
Example: The company spent about $7 million on a 30-second Super Bowl ad featuring a talking dog.
Usually written without a period; British English also uses the clipping "advert." The short form ad dates from the 19th century. Digital advertising, including search and social media ads, now accounts for most global ad spending. It should not be confused with A.D. (Anno Domini), which shares the same page.
3. Atopic dermatitis
Medical · Dermatology Abbreviations
Chronic, itchy inflammatory skin disease, the most common form of eczema, usually starting in infancy or childhood with dry skin and red patches on the cheeks, skin creases and limbs. It often occurs with asthma, allergic rhinitis and food allergy, and flares are triggered by irritants, allergens, heat and stress.
Example: Moderate AD, EASI 18, sleep disrupted; continue emollients and TCS, start dupilumab.
"Atopic" refers to a tendency toward allergic diseases; the sequence from eczema to food allergy, asthma and hay fever is called the atopic march. Mutations in the skin barrier protein filaggrin increase risk. Treatments include moisturizers, topical steroids and calcineurin inhibitors, and since 2017 biologics and JAK inhibitors for moderate to severe disease. In neurology AD means Alzheimer's disease, and in older prescriptions the right ear.
4. Advance directive
Medical · Emergency Medicine Abbreviations
Legal document in which a person states wishes for future medical care and/or names someone to decide for them if they cannot. Living wills and health care powers of attorney are common forms.
Example: AD on file names daughter as agent; scanned into EHR.
The federal Patient Self-Determination Act of 1990 requires hospitals and nursing homes participating in Medicare to inform patients of their rights to make advance directives. An AD guides decisions but is not itself an order like DNR or POLST. In pharmacy, AD means right ear and is listed by ISMP as error-prone.
5. Alzheimer's disease
Medical · Neurology Abbreviations
Most common cause of dementia, accounting for an estimated 60 to 80 percent of cases, marked by progressive memory loss and decline in thinking, language and daily function. The brain accumulates amyloid plaques and tau tangles years before symptoms begin.
Example: Progressive short-term memory loss over 3 years, MoCA 18, amyloid PET positive: early AD.
German psychiatrist Alois Alzheimer described the first case, Auguste Deter, in 1906. About 7 million Americans aged 65 and older are estimated to live with Alzheimer's dementia. Anti-amyloid antibodies lecanemab (full FDA approval in 2023) and donanemab (2024) modestly slow decline in early disease but require MRI monitoring for brain swelling and bleeding. AD can also mean atopic dermatitis, advance directive or anno Domini.
6. Assistive device
Medical · Rehabilitation Abbreviations
Any device used to help a patient walk or perform tasks safely, especially walkers, canes and crutches in therapy notes. Device choice depends on balance, strength, weight-bearing status and environment.
Example: Ambulated 50 ft without AD, two LOB requiring Min A; recommend FWW.
Therapy goals often specify "with least restrictive AD". In pharmacy, AD means right ear (auris dextra), an abbreviation ISMP lists as error-prone, and in neurology Alzheimer's disease. Assistive technology for communication or computer access is usually called AT.
7. Active Directory
Technology & Computing · Computer Abbreviations
Microsoft's directory service for Windows networks, storing user accounts, computers, groups and policies and handling sign-in authentication across a domain. Most large organizations running Windows manage employee logins through it.
Example: Your account is locked in AD; I'll unlock it and you can try signing in again.
Active Directory debuted with Windows 2000 Server and relies on LDAP, Kerberos and DNS. Its cloud counterpart, formerly Azure AD, was renamed Microsoft Entra ID in 2023. Servers that host AD are called domain controllers, and settings reach machines through Group Policy. Attackers prize AD because compromising it can give control of an entire network.
8. Active duty
Military · Military Term Abbreviations
Full-time service in the armed forces, as distinct from part-time service in the National Guard or reserves. Reservists can also be ordered to active duty for training, deployments or emergencies.
Example: After four years on AD he joined the Guard to finish his degree.
Military records often abbreviate active duty as AD, as in "AD Army" or "AD dates." Active duty for training (ADT) and active duty for operational support (ADOS) are reserve-component variants. In the Navy, AD is also the aviation machinist's mate rating.
9. Andorra
Geography & Places · Country Code Abbreviations
Tiny co-principality in the Pyrenees between France and Spain, whose joint heads of state are the Bishop of Urgell and the President of France. Its capital, Andorra la Vella, is the highest capital city in Europe at about 1,023 metres.
Example: Ski passes bought on the resort's .ad website are valid across all of Andorra.
The alpha-3 code is AND, which can trip up software that treats it as the word and. Andorra uses the euro without being an EU member, and Catalan is its only official language.
10. Autosomal dominant
Science & Engineering · Genetics Abbreviations
Inheritance pattern in which a single copy of a variant on a non-sex chromosome is enough to cause a trait or disorder. Each child of an affected parent has a 50% chance of inheriting it, and the condition typically appears in every generation, as with Huntington's disease and Marfan syndrome.
Example: The pedigree shows an AD pattern, with affected individuals in four successive generations.
Penetrance can be incomplete, so some carriers of a dominant variant never show symptoms, as with many BRCA1 carriers. New mutations can produce dominant conditions in children of unaffected parents, as in most cases of achondroplasia. In other contexts AD means anno Domini or advertisement.
11. Aggregate demand
Business & Finance · Economics Abbreviations
Total demand for goods and services in an economy at a given overall price level, made up of household consumption, business investment, government spending and net exports. The AD curve slopes downward in macroeconomic models.
Example: Tax cuts and higher government spending shifted AD to the right, lifting output and prices.
AD is analyzed together with aggregate supply in the AD-AS model taught in introductory macroeconomics. Keynesian economics emphasizes managing AD through fiscal and monetary policy. Outside economics, AD most often means anno Domini in dates.
12. Attack damage
Texting & Internet Slang · Gaming Slang Abbreviations
Physical damage stat in League of Legends and similar games, boosted by weapons and items, as opposed to AP (ability power). Champions are described as "AD" or "AP."
Example: Build armor this game, their whole team is AD.
Countering an "all-AD" team with armor is a basic strategy. "AD" also appears in "ADC" (attack damage carry). Outside gaming, AD often means "anno Domini" or advertisement, which context makes clear.
13. Aviation Machinist's Mate
Military · US Navy and Coast Guard Rating Abbreviations
Engine specialists of naval aviation, maintaining and repairing jet engines, turboprops, fuel systems, propellers and related aircraft components. Some ADs fly as aircrew or plane captains responsible for preparing an aircraft for flight.
Example: AD2 Fisher replaced the fuel control unit before the morning launch.
The rating descends from the World War I-era aviation machinist's mate. Navy aviation rates are usually grouped by system: ADs handle power plants, AMs airframes and hydraulics, AEs electrical systems and ATs avionics. In personnel usage, AD also means active duty.
14. Assistant director
Arts & Entertainment · Film, Television and Theater Abbreviations
Crew member who manages the shooting schedule and keeps the set running on time, calling out "rolling" and "quiet on set." The first AD is the director's right hand; second ADs handle call sheets and cast logistics.
Example: The first AD called a 30-minute lunch and reset for the next scene.
Assistant directors do not direct actors; their job is logistics and safety on set. Call sheets, prepared by the second AD, list each day's scenes, cast and call times. In history AD means Anno Domini.
15. Auris dextra (right ear)
Medical · Medication Route Abbreviations
Otic abbreviation meaning the right ear, used in ear drop orders and audiology records. ISMP lists AD as error-prone because it has been confused with OD (right eye), causing ear drops to be instilled in the eye.
Example: Ofloxacin otic 5 drops AD BID x 7 days.
Latin "auris dextra". ISMP recommends writing "right ear". Otic preparations are not made to the sterility and pH standards required for the eye and can harm it, whereas ophthalmic drops may sometimes be prescribed for use in the ear. AD has many unrelated medical meanings, including Alzheimer disease and atopic dermatitis.
Related abbreviations
More religious term abbreviations
- ACNA – Anglican Church in North America
- AH – Anno Hegirae (in the year of the Hijra)
- AM – Anno Mundi (in the year of the world)
- AMDG – Ad maiorem Dei gloriam (for the greater glory of God)
- AME – African Methodist Episcopal Church
- AMP – Amplified Bible
- AS – Alayhi as-salam (peace be upon him)
- ASV – American Standard Version
See all 78 religious term abbreviations →
More everyday abbreviations
- A-OK – All OK (perfectly fine)
- acct. – Account
- aka – Also known as
- amt. – Amount
- ans. – Answer
- approx. – Approximately
- appt. – Appointment
- Ass'n – Association
See all 82 everyday abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.