ID
Abbreviation with 8 meanings
| Stands for | Idaho |
|---|---|
| Meanings | 8 |
| Categories | Geography & Places, Writing & Everyday, Law & Legal, Medical, Science & Engineering |
| Also written | Id., id. |
ID has eight meanings. The most common are Idaho (US state) and Identification (everyday); it can also stand for Idem (the same), Infectious diseases, Intellectual disability, Indonesia and Inside diameter, plus 1 more listed below.
Meanings of ID at a glance
| # | ID stands for | Context |
|---|---|---|
| 1 | Idaho | Geography & Places › US State |
| 2 | Identification | Writing & Everyday › Everyday |
| 3 | Idem (the same) | Law & Legal › Legal Citation |
| 4 | Infectious diseases | Medical › Medical Specialty |
| 5 | Intellectual disability | Medical › Mental Health & Psychiatry |
| 6 | Indonesia | Geography & Places › Country Code |
| 7 | Inside diameter | Science & Engineering › Engineering |
| 8 | Intradermal | Medical › Medication Route |
1. Idaho
Geography & Places · US State Abbreviations
The Gem State joined the Union on July 3, 1890, as the 43rd state. Boise is the capital and largest city, the Snake River Plain supports one of the country's main potato-growing regions, and Idaho produces roughly a third of the US potato crop.
Example: The seed potatoes ship from a farm near Idaho Falls, ID 83402.
AP style never abbreviates Idaho; very old references show Ida., now obsolete. The postal code ID dates from 1963. Because ID usually means identification, web forms are clearer with a state drop-down than free text, and ID is also Indonesia's ISO country code and .id domain.
2. Identification
Writing & Everyday · Everyday Abbreviations
Refers to a document that proves who a person is, such as a driver's license, passport or national identity card, and more broadly to identification itself. Bars, airports, banks and polling places routinely ask to see ID.
Example: You'll need a valid photo ID and a boarding pass to get through airport security.
As a verb, "to ID someone" means to check their identification or to identify them, as in "police IDed the suspect." Since May 2025, US domestic flights have required a REAL ID-compliant license or another accepted document such as a passport. Many countries issue compulsory national ID cards, while the United States and the United Kingdom do not. In postal use, ID is Idaho.
3. Idem (the same) (Id.)
Law & Legal · Legal Citation Abbreviations · also used in general use
Short-form citation pointing to the authority cited immediately before, used to avoid repeating a full citation. Followed by "at" and a page, it cites a different page of the same source ("Id. at 45"); used alone, it means the same page as the preceding citation.
Example: The court found the clause ambiguous. Id. at 48. It then construed the ambiguity against the drafter. Id.
From Latin "idem", "the same". Bluebook Rule 4.1 requires it to be italicized or underlined, and capitalized when it begins a citation sentence. It cannot be used if the preceding citation contained more than one source. Unlike academic styles, the Bluebook does not use "ibid."; id. does that job. No comma follows it before "at".
4. Infectious diseases
Medical · Medical Specialty Abbreviations
Subspecialty of internal medicine or pediatrics dedicated to complex infections, including HIV, tuberculosis, bone and joint infections, endocarditis, infections in transplant and cancer patients, travel medicine and antibiotic-resistant organisms. Adult ID training is a two-year fellowship after internal medicine residency.
Example: ID recommends six weeks of IV cefazolin via PICC for MSSA vertebral osteomyelitis.
ID physicians typically lead hospital antimicrobial stewardship and infection prevention programs, and their consultation has been linked to better survival in Staphylococcus aureus bacteremia. The Infectious Diseases Society of America (IDSA) publishes many treatment guidelines. On prescriptions ID means intradermal, and in everyday use it means identification.
5. Intellectual disability
Medical · Mental Health & Psychiatry Abbreviations
Neurodevelopmental disorder with deficits in intellectual functions such as reasoning, problem solving and learning, together with deficits in adaptive functioning, beginning during the developmental period. Severity (mild, moderate, severe, profound) is now based mainly on adaptive functioning rather than IQ alone.
Example: Mild ID with Down syndrome; supported employment and guardianship review.
The older term "mental retardation" was replaced in US federal law by Rosa's Law in 2010 and in DSM-5 in 2013; ICD-11 uses "disorders of intellectual development". About 1 percent of people have ID. Genetic testing often identifies a cause, such as fragile X syndrome. In other medical contexts ID means infectious disease or intradermal.
6. Indonesia
Geography & Places · Country Code Abbreviations
World's largest archipelagic state, with about 17,000 islands and the fourth-largest population on Earth. Jakarta is the capital, with a planned new capital, Nusantara, under construction on Borneo; the alpha-3 code is IDN and the rupiah trades as IDR.
Example: Shopee sellers ship nationwide within ID from warehouses in Jakarta and Surabaya.
The IOC code is INA. In US addresses ID means Idaho, and in everyday English it means identification. The language code id stands for Indonesian, so id-ID is Indonesian as used in Indonesia.
7. Inside diameter
Science & Engineering · Engineering Abbreviations
Diameter measured across the inner surfaces of a pipe, tube, hole, bearing or ring, determining flow capacity and what fits inside. ID equals the outside diameter minus twice the wall thickness.
Example: The hose has a 3/4-inch ID and is rated for 300 psi.
O-rings are specified by ID and cross-section, and bearings by bore (ID), outside diameter and width. Engineering drawings often mark diameters with the symbol Ø. The abbreviation ID more commonly means identification in everyday use.
8. Intradermal
Medical · Medication Route Abbreviations
Injection into the dermis, just beneath the epidermis, producing a small raised bleb. It is used for the tuberculin skin test, allergy skin testing, some vaccines and local anesthetic wheals before procedures.
Example: Tuberculin PPD 0.1 mL ID left forearm; read in 48-72 hours.
ID injections use a fine 26- or 27-gauge needle inserted at a shallow angle of about 5 to 15 degrees. The Mantoux tuberculin test injects 5 tuberculin units in 0.1 mL. The mpox vaccine Jynneos was authorized for intradermal dosing in 2022 to stretch limited supplies. ID also means infectious disease and identification.
Related abbreviations
More US state abbreviations
See all 51 US state abbreviations →
More everyday abbreviations
- fdn. – Foundation
- govt. – Government
- HQ – Headquarters
- ICE – In case of emergency
- incl. – Including or included
- info – Information
- Inst. – Institute
- intl. – International
See all 82 everyday abbreviations →
This entry is for general education and is not medical or legal advice. Abbreviation use varies between institutions; always confirm in context.