| J/M | Jettison Motor | - | Organizations |
| JAEIC | Joint Atomic Energy Intelligence Committee | - | Organizations |
| JAN | Joint Army-Navy | - | Organizations |
| JAS | Journal Of Aerospace Science | - | Organizations |
| JB | Junction Box | - | Organizations |
| JCL | Job Control Language | - | Organizations |
| JCP | Joint Power Conditions | - | Organizations |
| JCT | Junction | - | Organizations |
| JED | Julian Ephemeris Data | - | Organizations |
| JETS | Joint Electronics Type (Designation) System | - | Organizations |
| JETT | Jettison | - | Organizations |
| JIR | Job Improvement Request | - | Organizations |
| JO | Job Order | - | Organizations |
| JOD | Joint Occupancy Data | - | Organizations |
| JOD | Joint Occupancy Date | - | Organizations |
| JOIP | Joint Operations Interface Procedure | - | Organizations |
| JOP | Joint Operating Procedure | - | Organizations |
| JOP | Jupiter Orbiter Probe-Galilee | - | Organizations |
| JOR | Job Order Request | - | Organizations |
| JOULE | (SI UJoule (SI Unit) | - | Organizations |
| JOVIAL | Joules Own Version International Algebraic Language | - | Organizations |
| JP | Jet Propellant | - | Organizations |
| JP | Jet Propulsion | - | Organizations |
| JPC | Joint Power Condition | - | Organizations |
| JPIC | Joint Program Integration Committee | - | Organizations |
| JPL | Jet Propulsion Laboratory | - | Organizations |
| JPL | Jet Propulsion Laboratory | - | Organizations |
| JPOC | JSC Payload Operations Center | - | Organizations |
| JPP | Joint Program Plan | - | Organizations |
| JRB | Joint Review Board | - | Organizations |
| JSC | Johnson Space Center | - | Organizations |
| JSL | Jet Select Logic | - | Organizations |
| JSLWG | Joint Spacelab Working Group | - | Organizations |
| JST | Joint Systems Test | - | Organizations |
| JTA | Job Task Analysis | - | Organizations |
| JTG | Joint Training Group | - | Organizations |
| JURG | Joint Users Requirements Group | - | Organizations |
