| J | TENS -Joint-Tactical Exploitation Of National Capabilities | - | Astronomy |
| J | Joule | - | Astronomy |
| J1 | Joint [Manpower &] Personnel Directorate | - | Astronomy |
| J2 | Joint Intelligence Directorate | - | Astronomy |
| J2EE | Java 2 Platform | - | Astronomy |
| J2ME | Java 2 Platform | - | Astronomy |
| J2SE | Java 2 Platform | - | Astronomy |
| J3 | Joint Operations Directorate | - | Astronomy |
| J4 | Joint Logistics Directorate | - | Astronomy |
| J5 | Joint Strategic Plans & Policy Directorate | - | Astronomy |
| J6 | Joint Information Technology Directorate (Command | - | Astronomy |
| J7 | Joint Operational Plans & Interoperability Directorate | - | Astronomy |
| J8 | Joint Force Structure | - | Astronomy |
| J9 | Joint Public Affairs Directorate (Civilian-Military Cooperation) | - | Astronomy |
| JA | Japan (FIPS 10-4 Country Code) | - | Astronomy |
| JA | Japanese Language (ISO 639-1 Code) | - | Astronomy |
| JAFT | Just A Field Test | - | Astronomy |
| JAG | Judge Advocate General (military Law) | - | Astronomy |
| JAL | Japan Airlines | - | Astronomy |
| JAM | Jamaica (ISO 3166 Trigram) | - | Astronomy |
| JAMA | Journal Of The American Medical Association | - | Astronomy |
| JANUS | Joint Academic Network Using Satellites (UK) - Joint Army Navy Uniform Simulation -Joint Army-Navy Staff - Just ANother Useless Simulation (Note: The U.S. Army Janus Simulation Is Not An Acronym) | - | Astronomy |
| JATO | Jet-Assisted Take-Off | - | Astronomy |
| JAV | Javanese Language (ISO 639-2 Code) | - | Astronomy |
| JB | Junior Branch | - | Astronomy |
| JBFSA | Joint Blue Force Situational Awareness | - | Astronomy |
| JCATS | Joint Conflict And Tactical Simulation (djay-catts) | - | Astronomy |
| JCDB | Joint Common Data Base | - | Astronomy |
| JCDS | Joint Chiefs Of The Defence Staff | - | Astronomy |
| JCIDS | Joint Capabilities Integration And Development System | - | Astronomy |
| JCIET | Joint Combat Identification Evaluation Team | - | Astronomy |
| JCL | Job Control Language | - | Astronomy |
| JCP | Java Community Process | - | Astronomy |
| JCPM | Java Child Process Manager - Jesus Christ Prison Ministry | - | Astronomy |
| JCS | Joint Chiefs Of Staff | - | Astronomy |
| JD | Jack Daniels (whiskey) - Julian Day - Juris Doctor (Latin | - | Astronomy |
| JDAM | Joint Direct Attack Munition (djay-dam) | - | Astronomy |
| JDBC | Java Data Base Connectivity | - | Astronomy |
| JDCC | UK Joint Doctrine And Concepts Centre | - | Astronomy |
| JDEM | Joint Dark Energy Mission | - | Astronomy |
| JDK | Java Development Kit | - | Astronomy |
| JDL | Jewish Defense League | - | Astronomy |
| JE | Jersey (FIPS 10-4 Territory Code) | - | Astronomy |
| JEB | James Ewell Brown Stuart - Jeb Bush - Jeb Stuart - John Ellis Bush | - | Astronomy |
| JEE | Java Platform | - | Astronomy |
| JEFX | Joint Expeditionary Force EXperiment | - | Astronomy |
| JET | Joint European Torus | - | Astronomy |
| JEZ | Joint Engagement Zone | - | Astronomy |
| JFACC | Joint Force Air Component Commander | - | Astronomy |
| JFACTSU | U.S. Joint Forward Air Control Training And Standards Unit | - | Astronomy |
| JFC | Joint Force Commander | - | Astronomy |
| JFCOM | U.S. Joint Forces Command (jiff-comm) | - | Astronomy |
| JFET | Junction Field-Effect Transistor (jay-fett) | - | Astronomy |
| JFHQ | NCR -Joint Force Headquarters National Capital Region | - | Astronomy |
| JFK | John Fitzgerald Kennedy Or The Airport Named After Him. | - | Astronomy |
| JFLCC | Joint Force Land Component Commander | - | Astronomy |
| JFMCC | Joint Force Maritime Component Commander | - | Astronomy |
| JFO | Journal Of Field Ornithology | - | Astronomy |
| JFSOCC | Joint Force Special Operations Component Commander | - | Astronomy |
| JFTX | Joint Field Training Exercise | - | Astronomy |
| JH | Japan Highway Public Corporation | - | Astronomy |
| JI | Joint Implementation | - | Astronomy |
| JIB | Joint Information Bureau | - | Astronomy |
| JIC | Joint Intelligence Centre | - | Astronomy |
| JINI | Java Intelligent Network Infrastructure | - | Astronomy |
| JITC | Joint Interoperability Test Command | - | Astronomy |
| JIVE | Joint Institute For VLBI (Very Long Baseline Interferometry) In Europe | - | Astronomy |
| JK | Jedi Knight - Just Kidding -Spanair (IATA Airline Designator) | - | Astronomy |
| JL | Japan Airlines (IATA Airline Designator) | - | Astronomy |
| JLA | Justice League Of America | - | Astronomy |
| JM | Jamaica (FIPS 10-4 Country Code; ISO 3166 Digram) | - | Astronomy |
| JMD | Jamaican Dollar (ISO 4217 Currency Code) | - | Astronomy |
| JMS | Java Message Service | - | Astronomy |
| JN | Jan Mayen Island (FIPS 10-4 Territory Code) | - | Astronomy |
| JNI | Java Native Interface | - | Astronomy |
| JNLP | Java Network Launch Protocol | - | Astronomy |
| JO | Jordan (FIPS 10-4 Country Code; ISO 3166 Digram) | - | Astronomy |
| JOA | Joint Operations Area | - | Astronomy |
| JOD | Jordanian Dinar (ISO 4217 Currency Code) | - | Astronomy |
| JOPES | Joint Operations Planning And Execution System | - | Astronomy |
| JOR | Jordan (ISO 3166 Trigram) | - | Astronomy |
| JOTS | Joint Operations Tactical System | - | Astronomy |
| JP | Japan (ISO 3166 Digram) -Justice Of The Peace | - | Astronomy |
| JPEG | Joint Photographic Experts Group (djay-peg) | - | Astronomy |
| JPL | Jet Propulsion Laboratory | - | Astronomy |
| JPN | Japan (ISO 3166 Trigram) | - | Astronomy |
| JPN | Japanese Language (ISO 639-2 Code) | - | Astronomy |
| JPOW | Joint Project Optic Windmill | - | Astronomy |
| JPY | Japanese Yen (ISO 4217 Currency Code) | - | Astronomy |
| JQ | Jetstar Airways (IATA Airline Designator) -Johnny Quick -Johnston Atoll (FIPS 10-4 Territory Code) -Jonny Quest - Joshua Quagmire | - | Astronomy |
| JRA | Japanese Red Army - Joint Rear Area | - | Astronomy |
| JRDF | Joint Rapid Deployment Forces | - | Astronomy |
| JRE | Java Runtime Environment | - | Astronomy |
| JREF | James Randi Educational Foundation | - | Astronomy |
| JROC | Joint Requirements Oversight Council | - | Astronomy |
| JROCM | JROC Memorandum | - | Astronomy |
| JRRF | Joint Rapid Reaction Forces | - | Astronomy |
| JSAF | Joint Semi-Automated Forces (jay-saff) | - | Astronomy |
| JSCSC | Joint Services Command And Staff College | - | Astronomy |
| JSD | Juris Scientiae Doctor (Latin | - | Astronomy |
