EM
Abbreviation with 8 meanings
| Stands for | Emergency medicine |
|---|---|
| Meanings | 8 |
| Categories | Medical, Science & Engineering, Business & Finance, Military, Units & Measurements |
EM has eight meanings. The most common are Emergency medicine (medical specialty) and Erythema migrans (dermatology); it can also stand for Electromagnetic, Erythema multiforme, Emerging markets, Engineering manager and Electrician's Mate, plus 1 more listed below.
Meanings of EM at a glance
| # | EM stands for | Context |
|---|---|---|
| 1 | Emergency medicine | Medical › Medical Specialty |
| 2 | Erythema migrans | Medical › Dermatology |
| 3 | Electromagnetic | Science & Engineering › Physics |
| 4 | Erythema multiforme | Medical › Dermatology |
| 5 | Emerging markets | Business & Finance › Stock Market & Investing |
| 6 | Engineering manager | Business & Finance › Job Title |
| 7 | Electrician's Mate | Military › US Navy and Coast Guard Rating |
| 8 | Expectation-maximization | Units & Measurements › Statistics |
1. Emergency medicine
Medical · Medical Specialty Abbreviations
Specialty caring for patients with acute, undifferentiated illness and injury in emergency departments, from resuscitation and major trauma to minor complaints. In the US it was recognized as the 23rd medical specialty in 1979, and residency lasts three or four years.
Example: EM physician activated the trauma team before the ambulance arrived.
Board certification is by the American Board of Emergency Medicine (ABEM). Subspecialties include pediatric emergency medicine, medical toxicology, EMS, sports medicine and critical care. US emergency departments must screen and stabilize patients regardless of ability to pay under the 1986 EMTALA law. In physics EM means electromagnetic.
2. Erythema migrans
Medical · Dermatology Abbreviations
Expanding red rash, at least 5 cm across, that appears at the site of a tick bite 3 to 30 days later and is the hallmark of early Lyme disease. It may clear in the center to form a bull's-eye pattern, though most rashes in the US are uniformly red.
Example: EM 9 cm on left thigh after camping in Connecticut; treat for Lyme disease with doxycycline 10 days.
Because the rash is diagnostic in endemic areas, treatment starts without blood tests, which are often negative this early. Multiple EM lesions indicate the bacteria have spread. It differs from a small red bump at the bite site that fades within a day or two, which is a hypersensitivity reaction. In other dermatology notes EM means erythema multiforme.
3. Electromagnetic
Science & Engineering · Physics Abbreviations
Relating to electricity and magnetism and their interaction, as in EM waves, the EM spectrum or the EM force. Electromagnetism is one of the four fundamental forces, responsible for light, chemistry, magnetism and the structure of everyday matter.
Example: EM interference from the motor drive was disrupting the sensor readings.
The electromagnetic force is carried by photons and is about 10^36 times stronger than gravity between two protons. Maxwell's equations of the 1860s unified electricity, magnetism and light. In engineering, EM simulation software models antennas, circuit boards and shielding.
4. Erythema multiforme
Medical · Dermatology Abbreviations
Acute, often recurrent skin reaction producing target-shaped lesions with three concentric zones, mainly on the hands, feet and limbs, sometimes with mouth sores. Herpes simplex virus infection is the most common trigger.
Example: Recurrent targetoid lesions on palms after cold sores: HSV-associated EM, suppressive valacyclovir.
EM minor lacks significant mucosal involvement, while EM major involves mucous membranes. It is now considered distinct from Stevens-Johnson syndrome, which is usually drug-induced. Episodes typically resolve in two to four weeks. In Lyme disease EM refers to erythema migrans.
5. Emerging markets
Business & Finance · Stock Market & Investing Abbreviations
Developing economies with growing financial markets, such as China, India, Brazil, Taiwan, South Korea, Mexico and South Africa, as classified by index providers. EM stocks and bonds offer higher growth potential but greater political, currency and liquidity risks.
Example: EM equities rallied as the dollar weakened and commodity prices recovered.
Antoine van Agtmael of the International Finance Corporation coined the term "emerging markets" in 1981. Index providers disagree on some classifications: MSCI treats South Korea as emerging, while FTSE Russell classifies it as developed. EM debt can be issued in dollars (hard currency) or in local currencies.
6. Engineering manager
Business & Finance · Job Title Abbreviations
Manager who leads a team of software or hardware engineers, handling hiring, career development, performance, team processes and delivery while partnering with product managers on priorities. EMs may or may not write code themselves.
Example: Our EM runs one-on-ones every week and protects Fridays for focused work.
Technology companies often have parallel career ladders, so a strong engineer can progress as an individual contributor (staff or principal engineer) instead of becoming an EM. Engineering managers typically report to a director of engineering. In investing, EM means emerging markets.
7. Electrician's Mate
Military · US Navy and Coast Guard Rating Abbreviations
Shipboard electricians who operate and repair generators, switchboards, motors, lighting and power distribution systems. Nuclear-trained electrician's mates (EMN) operate the electrical plant on reactor-powered carriers and submarines.
Example: EM3 Blake isolated the ground fault on the number two switchboard before the inspection.
The badge shows a globe. Electrician's mates on conventionally powered ships often move between engineering departments and auxiliary systems. In physics EM means electromagnetic, and in typography an em is a unit of width, unrelated to this rating.
8. Expectation-maximization
Units & Measurements · Statistics Abbreviations
An iterative algorithm for maximum likelihood estimation when data are incomplete or involve hidden variables. It alternates an E-step, which computes expected values of the missing parts, with an M-step, which maximizes the likelihood.
Example: Cluster memberships were estimated with the EM algorithm for a Gaussian mixture model.
Arthur Dempster, Nan Laird and Donald Rubin formalized the algorithm in a 1977 paper. Each iteration never decreases the likelihood, but EM can settle on a local maximum, so analysts try multiple starting points. Applications include mixture models, hidden Markov models and imputing missing data.
Related abbreviations
More medical specialty abbreviations
- CCM – Critical care medicine
- CT – Cardiothoracic (surgery)
- Derm – Dermatology
- ECFMG – Educational Commission for Foreign Medical Graduates
- Endo – Endocrinology
- ENT – Ear, nose and throat (otolaryngology)
- FM – Family medicine
- FP – Family physician (family practice)
See all 47 medical specialty abbreviations →
More dermatology abbreviations
- DLQI – Dermatology Life Quality Index
- DRESS – Drug reaction with eosinophilia and systemic symptoms
- EASI – Eczema Area and Severity Index
- ED&C – Electrodesiccation and curettage
- GA – Granuloma annulare
- HA – Hyaluronic acid (filler)
- HS – Hidradenitis suppurativa
- ICD – Irritant contact dermatitis
See all 52 dermatology abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.