| J-OE | IEEE Journal of Oceanic Engineering 
| Others |
| J-POP | Japanese Pop
| Others |
| J-QE | IEEE Journal of Quantum Electronics
| Others |
| J-RA | IEEE Journal on Robotics and Automation
| Others |
| J-RPG | Japanese Role Playing Game
| Others |
| J-S | July through September
| Others |
| J-SAC | IEEE Journal on Selected Areas in Communications
| Others |
| J-SC | IEEE Journal of Solid-state Circuits
| Others |
| J-SEAD | Joint Suppression of Enemy Air Defenses
| Others |
| J-STQE | IEEE Journal on Selected Topics in Quantum Electronics
| Others |
| J-T-W | Journey To Work
| Others |
| J-WALK | John Walkenbach and Associates
| Others |
| J. Int. Environ. Appl. Sci. | Journal of International Environmental Application and Science
| Others |
| J.D. | Doctor of Laws [Lat.]
| Others |
| J.D. | Juris Doctor
| Others |
| J.D. | Other Intelligence Systems Pms (Integrator)
| Others |
| J.L.Y.A.S.D.W | Jesus Loves You All So Do We
| Others |
| J.M | Just Mentioned
| Others |
| J.S.D | Doctor of Juristic Science
| Others |
| J/cg | Joules Per Centigram
| Others |
| J/D | Judgment for the Defendant
| Others |
| J/DEG | Joule Per Degree
| Others |
| J/g | Joules Per Gram
| Others |
| J/kg | Joules Per Kilogram
| Others |
| J/M | Jettison Motor
| Others |
| J/mg | Joules Per Milligram
| Others |
| J/O | Jerking Off
| Others |
| J2-CI | Joint Counterintelligence Office
| Others |
| J2C | Java 2 Connector
| Others |
| J2CA | J2ee Connector Architecture
| Others |
| J2EE | Java 2 Enterprise Edition
| Others |
| J2EE | Java 2 Platform Enterprise Edition
| Others |
| J2K | Jeep J2000
| Others |
| J2K | Jpeg 2000
| Others |
| J2LUK | Just To Let You Know
| Others |
| J2ME | Java 2 Micro Edition
| Others |
| J2ME | Java 2 Mobile Enterprise
| Others |
| J2ME | Java 2 Platform Micro Edition
| Others |
| J2ME | Java 2 Platform Mobile Edition
| Others |
| J2RE | Java 2 Platform Runtime Environment
| Others |
| J2SE | Java 2 Platform Standard Edition
| Others |
| J2SE | Java 2 Standard Edition
| Others |
| J2W | Jump to Win
| Others |
| J2WTK | Java 2 Platform Wireless Tool Kit
| Others |
| J4C | Just for Corvettes
| Others |
| J4F | Just For Fun
| Others |
| J4G | Just for Grins
| Others |
| J4J | Jews For Judaism
| Others |
| J4K | Jeep J4000
| Others |
| J4U | Just For You
| Others |