This list contains acronyms, initialisms, and pseudo-blends  that begin with the letter J.

For the purposes of this list:

• acronym = an abbreviation pronounced as if it were a word, e.g., SARS = severe acute respiratory syndrome, pronounced to rhyme with cars
• initialism = an abbreviation pronounced wholly or partly using the names of its constituent letters, e.g., CD = compact disc, pronounced cee dee
• pseudo-blend = an abbreviation whose extra or omitted letters mean that it cannot stand as a true acronym, initialism, or portmanteau (a word formed by combining two or more words).

(a) = acronym, e.g.: SARS – (a) severe acute respiratory syndrome

(i) = initialism, e.g.: CD – (i) compact disc

(p) = pseudo-blend, e.g.: UNIFEM – (p) United Nations Development Fund for Women

(s) = symbol (none of the above, representing and pronounced as something else; for example: MHz – megahertz)

Some terms are spoken as either acronym or initialism, e.g., VoIP, pronounced both as voyp and V-O-I-P.

(Main list of acronyms)

• J – (s) Joule

J0–9

• J1 – (s) Joint [Manpower &] Personnel Directorate
• J2 – (s) Joint Intelligence Directorate
• J2EE – (i) Java 2 Platform, Enterprise Edition
• J2ME – (i) Java 2 Platform, Micro Edition
• J2SE – (i) Java 2 Platform, Standard Edition
• J3 – (s) Joint Operations Directorate
• J4 – (s) Joint Logistics Directorate
• J5 – (s) Joint Strategic Plans & Policy Directorate
• J6 – (s) Joint Information Technology Directorate (Command, Control, Communications & Computer Systems)
• J7 – (s) Joint Operational Plans & Interoperability Directorate
• J8 – (s) Joint Force Structure, Resources, & Assessment Directorate
• J9 – (s) Joint Public Affairs Directorate (Civilian-Military Cooperation)

JA

• ja – (s) Japanese language (ISO 639-1 code)
• JA – (s) Japan (FIPS 10-4 country code)
• Jabodetabek – (p) Jakarta, Bogor, Depok, Tangerang, Bekasi (urban agglomeration of Jakarta)
• JAFT – (s) Just A Field Test
• JAG – (a) Judge Advocate General Corps (military law)
• JAL – (p) Japan Airlines
• JALLC – (a) Joint Analysis and Lessons Learned Centre (NATO)
• JAM – (s) Jamaica (ISO 3166 trigram)
• JAMA – (i) Journal of the American Medical Association
• JAOA- (i) Journal of the American Osteopathic Association
• JANET
  • (p) Joint Academic Network
  • (a) Just Another Non-Existent Terminal or Joint Air Network for Employee Transportation or Janet Airlines, a highly classified air shuttle service for the USAF, serving Area 51 and the Tonopah Test Range
• JANUS
  • (a) Joint Academic Network Using Satellites (UK)
  • Joint Army Navy Uniform Simulation
  • (p) Joint Army-Navy Staff
  • Just ANother Useless Simulation (Note: The U.S. Army Janus simulation is not an acronym)
• JAS
  • (i) Japan Air System, defunct Japanese airline
  • Japanese Agricultural Standard
  • Jericho Appreciation Society, former professional wrestling stable
  • Journal of Applied Statistics
• JATO – (a) Jet-Assisted Take-Off
• jav – (s) Javanese language (ISO 639-2 code)

JB

• JB – (i) Junior Branch
• JB – (i) Jail Bait
• JBFSA – (i) Joint Blue Force Situational Awareness
• JB- Justin Bieber

JC

• JCATS – (a) Joint Conflict And Tactical Simulation ("djay-catts")
• JCDB – (i) Joint Common Data Base
• JCDS – (i) Joint Chiefs of the Defence Staff
• JCIDS – (i) Joint Capabilities Integration and Development System
• JCIET – (i) Joint Combat Identification Evaluation Team
• JCL – (i) Job Control Language
• JCMOTF – (a) Joint Civil-Military Operations Task Force
• JCP – (a) Java Community Process
• JCPM – (i) Java Child Process Manager – Jesus Christ Prison Ministry
• JCS – (i) Joint Chiefs of Staff
• JCW – (i) Juggalo Championship Wrestling

JD

• JD
  • (i) Jack Daniel's (whiskey)
  • Julian day
  • Juris Doctor (Latin, "doctor of jurisprudence")
• JDAM – (a/i) Joint Direct Attack Munition ("djay-dam")
• JDBC – (i) Java Data Base Connectivity
• JDCC – (i) UK Joint Doctrine and Concepts Centre, now the Development, Concepts and Doctrine Centre (DCDC)
• JDEM – (i) Joint Dark Energy Mission
• JDK – (i) Java Development Kit
• JDL – (i) Jewish Defense League
• JDM
  • (i) Japanese domestic market, referring specifically to automobiles and parts
  • Java Data Mining
  • Joint design manufacturing

JE

• JE – (s) Jersey (FIPS 10-4 territory code)
• JEB
  • (a) James Ewell Brown (Stuart)
  • John Ellis Bush
• JEDP – (i) Jahwist, Elohist, Deuteronomist, Priestly (according to the documentary hypothesis, the sources of the Torah)
• JEE – (i) Java Platform, Enterprise Edition
• JEFX – (p) Joint Expeditionary Force eXperiment
• JEPD
  • (i) Jahwist, Elohist, Priestly, Deuteronomist
  • Jointly Exhaustive, Pairwise Disjoint
• JET – (a) Joint European Torus
• JEZ – (a) Joint Engagement Zone

JF

• JFACC – (i) Joint Force Air Component Commander
• JFACTSU – (a) U.K. Joint Forward Air Controller Training and Standards Unit
• JFC – (i) Joint Force Commander
• JFCOM – (p) U.S. Joint Forces Command ("jiff-comm")
• JFET – (i/a) Junction Field-Effect Transistor ("jay-fett")
• JFHQ-NCR – (i) Joint Force Headquarters National Capital Region
• JFK – (i) John Fitzgerald Kennedy or the airport named after him.
• JFLCC – (i) Joint Force Land Component Commander
• JFMCC – (i) Joint Force Maritime Component Commander
• JFO – (i) Journal of Field Ornithology
• JFSOCC – (i) Joint Force Special Operations Component Commander
• JFTX – (i) Joint Field Training Exercise
• JFF-Jamaica Football Federation

JH

• JH – (i) Japan Highway Public Corporation
• JH – (s) Jharkhand (Indian state code)

JI

• JI – (i) Joint Implementation
• JIB – (a) Joint Information Bureau
• JIC – (a) Joint Intelligence Centre
• JINI – (a) Java Intelligent Network Infrastructure
• JITC – (i) Joint Interoperability Test Command
• JIVE – (a) Joint Institute for VLBI (Very Long Baseline Interferometry) in Europe

JJ

• JJAP – (i) Japanese Journal of Applied Physics

JK

• JK – (i) Jedi Knight – Just Kidding – (s) Spanair (IATA airline designator) – Jammu & Kashmir (Indian state code)

JL

• JL – (s) Japan Airlines (IATA airline designator)
• JLA – (i) Justice League of America

JM

• JM – (s) Jamaica (FIPS 10-4 country code; ISO 3166 digram)
• JMD – (s) Jamaican dollar (ISO 4217 currency code)
• JMS – (i) Java Message Service

JN

• JN – (s) Jan Mayen Island (FIPS 10-4 territory code)
• JNI – (i) Java Native Interface
• JNLP – (i) Java Network Launch Protocol

JO

• JO – (s) Jordan (FIPS 10-4 country code; ISO 3166 digram)
• JOA – (a/i) Joint Operations Area
• JOD – (s) Jordanian dinar (ISO 4217 currency code)
• Jofa – (p) Jonssons fabriker (Swedish, "Jonsson's Factories")
• JOPES – (a) Joint Operations Planning and Execution System
• JOR – (s) Jordan (ISO 3166 trigram)
• JOTS – (a) Joint Operations Tactical System
• JSP – (a) Joint Services Publication

JP

• JP – (s) Japan (ISO 3166 digram) – (i) Justice of the Peace
• JPEG – (a) Joint Photographic Experts Group ("jay-peg")
• JPL – (i) Jet Propulsion Laboratory
• jpn – (s) Japanese language (ISO 639-2 code)
• JPN – (s) Japan (ISO 3166 trigram)
• JPOW – (i) Joint Project Optic Windmill
• JPY – (s) Japanese yen (ISO 4217 currency code)

JQ

• JQ – (s) Jetstar (IATA airline designator) – (i) Johnny Quick – (s) Johnston Atoll (FIPS 10-4 territory code) – (i) Jonny Quest – Joshua Quagmire

JR

• JRA – (i) Japanese Red Army – Joint Rear Area
• JRDF – (i) Joint Rapid Deployment Forces
• JRE – (i) Java Runtime Environment
• JREF – (i) James Randi Educational Foundation
• JROC – (i) Joint Requirements Oversight Council
• JROCM – (i) JROC Memorandum
• JRRF – (i) Joint Rapid Reaction Force
• JRSAI – Journal of the Royal Society of Antiquaries of Ireland

JS

• JSAF – (a) Joint Semi-Automated Forces ("jay-saff")
• JSAP – (i) Japan Society of Applied Physics
• JSCSC – (i) Joint Services Command and Staff College
• JSD – (i) juris scientiae doctor (Latin, "doctor of science of law")
• JSDF – (i) Japan Self-Defense Forces
• JSEAD – (i) Joint Suppression of Enemy Air Defence (see SEAD)
• JSF – (i) Joint Strike Fighter
• JSIMS – (p) Joint Simulation System
• JSOA – (i) Joint Special Operations Area
• JSOTF – (i) Joint Special Operations Task Force
• JSP – (i) JavaServer Page
• JSR – (i) Java Specification Request
• JSS – (i) Joint Support Ship Project
• JSTARS – (p) Joint Surveillance Target Attack Radar System ("djay-starz")

JT

• JT – (s) Johnston Atoll (ISO 3166 digram; obsolete 1986) – (i) Junior Technician (RAF) -- Jizz trumpet (Vulgar slang)
• JTAG – (p) Joint Test Action Group ("djay-tag")
• JTAGS – (p) Joint Tactical Ground Station ("djay-tagz")
• JTC – (i) Joint Training Confederation
• J-TENS – (a) Joint-Tactical Exploitation of National Capabilities
• JTF – (i) Joint Task Force
• JTFEX – (p) Joint Task Force Exercise
• JTIDS – (p) Joint Tactical Information Distribution System ("djay-tidz")
• JTLS – (i) Joint Theater Level Simulation
• JTMD – (i) Joint Theatre Missile Defence
• JTN – (s) Johnston Atoll (ISO 3166 trigram; obsolete 1986)
• JTRS – (a/i) Joint Tactical Radio System ("jitters")

JU

• JU – (s) Juan de Nova Island (FIPS 10-4 territory code)
• JUGFET – (p) JUnction Gate Field-Effect Transistor
• JUICE – (p) JUpiter ICy Moon Explorer
• JUO – (i) Joint Urban Operations

JV

• jv – (s) Javanese language (ISO 639-1 code)
• JV – (i) Joint Venture – Junior Varsity
• JVM – (i) Java virtual machine

JW

• JW – (i) Jehovah's Witnesses
• JWARS – (p) Joint Warfare System (simulation)
• JWP – (i) Joint Warfare Publication
• JWST – (i) James Webb Space Telescope

JY

• JY – (s) Japanese Yen

JZ

• JZ – (i) Joint Zone