| ac | Alternating current |
| ACCEL | Accelerometer or acceleration |
| ACE | Acceptance checkout equipment |
| ACK | Acknowledge |
| ACP | Audio control panel |
| ACS | Attitude control subsystem |
| A/D | Analog to digital |
| AGC | Automatic: gain control |
| AGE | Aerospace ground equipment |
| AH | Ampere hour |
| ALT | Altitude |
| AM | Amplitude modulation or ammeter |
| AMPL | Amplifier |
| ANL | Analog |
| AOA | Angle of attack |
| ARS | Attitude reference subsystem |
| ASCP | Attitude set control panel |
| ASI | Apollo standard initiator |
| ATT | Attitude or attenuator |
| AUTO | Automatic |
| AUX | Auxiliary |
| AVC | Automatic volume control |
| BAT | Battery |
| BCD | Binary coded decimal |
| BCN | Beacon |
| BECO | Booster engine cutoff |
| BMAG | Body-mounted attitude gyro |
| BPC | Boost protective cover |
| bps | Bits per second |
| BTU | British thermal unit |
| BU | Backup |
| BUR | Backup rate |
| CB | Circuit breaker |
| CCFT | Controlled current feedback transformer |
| CCTV | Closed-circuit television |
| CCW | Counterclockwise |
| C&D | Controls and displays |
| CDF | Confined detonating fuse |
| cfm | Cubic feet per minute |
| CG | Center of gravity |
| CHAN | Channel |
| CAT | Circuit |
| CL | Centerline |
| CLM | Core logic module |
| CM | Command module |
| CMC | Command module computer |
| CMD | Command |
| C/O | Checkout |
| CO2 | Carbon dioxide |
| COAS | Crew optical alignment sight |
| COAX | Coaxial |
| COI | Contingency orbit insertion |
| COMM | Communications |
| COMPR | Compressor |
| COMPEN | Compensator |
| COND | Condenser or conditioner |
| CONT | Control |
| CPLR | Coupler |
| CPS | Cycles per second |
| CRYO | Cryogenic |
| CSC | Cosecant computing amplifier |
| CSM | Command and service modules |
| CSS | Computer subsystem |
| C&W | Caution and warning subsystem |
| CW | Clockwise or continuous wave |
| CTE | Central timing equipment |
| CWG | Constant wear garment |
| D/A | DigitaI to anaIog |
| DAC | Digital-to-analog converter |
| DAP | Digital autopilot |
| DB | Deadband |
| db | Decibel |
| dc | Direct current |
| DECR | Decrease |
| DEG | Degree |
| DEMOD | Demodulate |
| DET | Detector or digital event timer |
| DISCR | Discriminator |
| DRI | Data rate indicator |
| DSE | Data storage equipment |
| DSIF | Deep Space Instrumentation Facility |
| DSKY | Display and keyboard |
| E | Elevation angle |
| ECA | Electronic control assembly |
| ECO | Engine combustion or engine cut |
| ECS | Environmental control subsystem |
| ECU | Environmental control unit |
| EDA | Electronic display assembly |
| EDS | Emergency detection subsystem |
| ELECT | Electronic |
| ELS | Earth landing subsystem |
| ELSC | Earth landing sequence controller |
| EMER | Emergency |
| EMI | Electromagnetic interference |
| EMS | Entry monitor subsystem |
| EMU | Extravehicular mobility unit |
| ENC | Encode |
| ENG | Engine |
| EOS | Emergency oxygen system |
| E&PL | Entry & post-landing |
| EPS | Electrical power subsystem |
| ERR | Error |
| ETR | Eastern test range |
| EU | Electronic unit |
| EVA | Extravehicular activity |
| FC | Fuel celI |
| fc | Center frequency |
| FCSM | Flight combustion stability monitor |
| FDAI | Flight director attitude indicator |
| FDT | Full duplex teletype circuit |
| F /F | Flip-flop |
| FHS | Forward heat shield |
| FLT | Flight |
| FLSC | Flexible linear shaped charge |
| FM | Frequency modulation |
| FOV | Field of vision |
| CQR | Flight qualification recorder |
| fs | Full scale |
| FSK | Frequency shift-keyed |
| FWD | Forward |
| G | Gravity |
| GA | Gyro assembly |
| gc | Gigacycles |
| G&C | Guidance and control |
| GDC | Gyro display coupler |
| GET | Ground elapsed time |
| GFE | Government-furnished equipment |
| GMBL | Gimbal |
| GN2 | Gaseous nitrogen |
| GND | Ground |
| GNCS | Guidance, navigation, and control subsystem |
| GPI | Gimbal position indicator |
| GSE | Ground support equipment |
| GSFC | Goddard Space Flight Center |
| ha | Apogee altitude |
| H2 | Hydrogen |
| He | Helium |
| HF | High frequency |
| Hg | Mercury |
| HGA | High-gain antenna |
| HI | High |
| hp | Perigee altitude |
| HR | Hydrogen relief or hour |
| HTR | Heater |
| Hz | Hertz (cycle per second) |
| IC | Intercom |
| ICDU | Inertial coupling data unit |
| IECO | inboard engine cutoff |
| IF | Intermediate frequency |
| IFN | In-fiight maintenance |
| IGA | Inner gimbal angle |
| IGN | Ignition |
| IMP | Impulse |
| IMU | Inertial measurement unit |
| INCR | Increase |
| IND | Indicator |
| INV | Inverter |
| IPB | Illuminated push button |
| IPS | Instrumentation power subsystem or inches per second |
| IRIG | Inertial rate integrating gyro |
| ISOL | Isolation |
| ISS | Inertial subsystem |
| IU | Instrument unit |
| JETT | Jettison |
| kbs | Kilobits per second |
| kc | Kilocycles |
| kHz | Kilohertz |
| KOH | Potassium hydroxide |
| KSC | Kennedy Space Center |
| kw | Kilowatt |
| LAT | Latitude |
| LCC | Launch Control Center |
| LDEC | Lunar docking events controller |
| LEA | Launch escape assembly |
| LEB | Lower equipment bay |
| LEM | Launch escape motor excursion module, old name for lunar module) |
| LES | Launch escape subsystem |
| LET | Launch escape tower |
| LEV | Launch escape vehicle |
| LF | Low frequency |
| LH2 | Liquid hydrogen |
| LHEB | Left-hand equipment bay |
| LHFEB | Left-hand forward equipment bay |
| LM | Lunar module |
| LMK | Landmark |
| LO | Low |
| LOR | Lunar orbit rendezvous |
| LOS | Line of sight, loss of signal |
| LOX | Liquid oxygen |
| LSB | Lower sideband |
| LSC | Linear-shaped charge |
| LSSC | LM separation sequence controller |
| LV | Launch vehicle or lift vector |
| MAN | Manual or manifold |
| MAX | Maximum |
| MAXQ | Maximum dynamic pressure |
| MCC | Mission Control Center |
| MDC | Main display console |
| MDF | MiId detonating fuse |
| MED | Medium |
| MESC | Master events sequence controller |
| MGA | Middle gimbal angle |
| mHz | Mega Hertz |
| MIKE | Microphone |
| mil | 1/1000 |
| MIN | Minimum |
| ML | Moldline |
| MMH | Monomethylhydrazine |
| MNA | Main bus A |
| MNB | Main bus B |
| MOD | Modulator |
| MOT | Motor |
| MS | Motor switch |
| MSC | Manned Spacecraft Center |
| MSFC | Marshall Space Flight Center |
| MSFN | Manned Space Flight Network |
| MTVC | Manned thrust vector control |
| mv | Millivolt |
| mw | Milliwatt |
| N2 | Nitrogen |
| NAV | Navigation |
| NB | Navigation base or narrow band |
| NEG | Negative |
| NEUT | Neutral |
| n.mi. | Nautical mile |
| NO. | Number |
| N.O. | Normally open |
| NON-ESS | Non-essential |
| NORM | Normal |
| NRZ | Non-return to zero |
| NSIF | Near-Space Instrumentation Facility |
| O2 | Oxygen |
| OCDU | Optics coupling data unit |
| OECO | Outboard engine cutoff |
| OGA | Outer gimbal angle |
| OH | Hydroxyl ion |
| O/L-RC | Overload - reverse current |
| OMNI | Omni-directional |
| OPT | Optics |
| OR | Oxygen relief |
| ORDEAL | Orbit rate drive electronics Apollo LM |
| OSC | Oscillator |
| OSS | Optics subsystem |
| O/V | Overvoltage |
| OXID | Oxidizer |
| PA | Power amplifier |
| PAM | Pulse amplitude modulation |
| PB | Push button |
| PCM | Pulse code modulation or pitch control motor |
| PCVB | Pyro continuity verification box |
| PDM | Pulse duration modulation |
| PF | Pulse frequency or powered flight |
| PGA | Pressure garment assembly |
| PH | Phase |
| pH | Hydrogen ion concentration |
| PIPA | Pulsed integrating pendulous accelerometer |
| PLBK | Playback |
| PLSS | Portable life support system |
| PM | Phase modulation |
| PMP | Premodulation processor |
| POS | Positive |
| POT | Potentiometer |
| PPM | Parts per million or pulse position modulation |
| PPS | Pulses per second |
| PRF | Pulse repetition frequency |
| PRI | Primary |
| PRN | Pseudo-random noise |
| PROP | Propellent |
| PS | Pressure switch |
| PSA | Power servo assembly |
| PSI | Pounds per square inch |
| PSIA | Pounds per square inch absolute |
| PSIG | Pounds per square inch gauge |
| PSK | Phase shift-keyed |
| PSO | Pad safety officer |
| PTT | Push to talk |
| PU | Propellant utilization |
| PUG | Propellant utilization gauging |
| PWR | Power |
| PYRO | Pyrotechnic |
| R | Range |
| RAD | Radiation dosage or radiator |
| RC | Rotation control or range command |
| RCDR | Recorder |
| RCS | Reaction control subsystem |
| RCSC | Reaction control subsystem controller |
| RCV | Receive |
| RCVR | Receiver |
| RECO | Rough engine cutoff |
| RECT | Rectifier |
| R&D | Research and development |
| REG | Regulator |
| REGEN | Regenerator |
| REL | Release |
| REV | Reverse |
| RF | Radio frequency |
| RFI | Radio frequency interference |
| RGA | Rate gyro assembly |
| RHC | Rotation hand control |
| RHEB | Right-hand equipment bay |
| RHFEB | Right-hand forward equipment bay |
| RJD | Reaction jet driver |
| RJ/EC | Reaction jet and engine control |
| RMS | Root mean square |
| RNG | Range |
| RNDZ | Rendezvous |
| ROT | Rotation |
| RT | Rendezvous radar transponder |
| RSI | Roll stability indicator |
| RSO | Range safety officer |
| RTC | Real-time command |
| RTV | Real-time television |
| RUPT | Interrupt |
| RZ | Return to zero |
| S/C | Spacecraft |
| SCE | Signal conditioning equipment |
| SCI | Scientific |
| SCO | Subcarrier oscillator |
| SCS | Stabilization and control subsystem |
| SCT | Scanning telescope |
| SEC | Second or secondary |
| SECO | S-iVB (third stage) engine cutoff |
| SECS | Sequential events control subsystem |
| SENS | Sensitivity |
| SEP | Separation or spacecraft electronic package |
| SEQ | Sequencer |
| SIG | Signal |
| SLA | Spacecraft-LM adapter |
| SLOS | Star line of sight |
| SM | Service module |
| SMJC | Service module jettison controller |
| SNSR | Sensor |
| SOV | Shutoff valve |
| SPEC | Specification |
| SPS | Service propulsion subsystem or samples per second |
| SSB | Single sideband |
| STBY | Standby |
| SW | Switch |
| SXT | Sextant |
| SYNC | Synchronization |
| TB | Talkback indicator |
| TC | Translation control |
| T/C | Telecommunications subsystem |
| T/D | Time delay |
| TEC | Transearth coast |
| TEI | Transearth injection |
| TEMP | Temperature |
| TFL | Time from launch |
| THC | Translation hand control |
| TIGN | Time of ignition |
| TJM | Tower jettison motor |
| TLC | Translunar coast |
| TLI | Translunar injection |
| TLM | Telemetry |
| TMG | Thermal meteoroid garment |
| TPAC | Telescope precision angle counter |
| T/R | Transmit-receive |
| TRNFR | Transfer |
| TTE | Time to event |
| TV | Thrust vector or television |
| TVC | Thrust vector control |
| TVSA | Thrust vector position servo amplifier |
| TWR | Tower |
| TWT | Traveling wave tube |
| UCD | Urine collection device |
| UDL | Up-data link |
| UDMH | Unsymmetrical dimethyl hydrazine |
| UHF | UItra high frequency |
| UPTL | Up-link telemetry |
| USBE | Unified S-band equipment |
| U/V | Undervoltage |
| V | Voice, volt, or velocity |
| VAC | Volts alternating current |
| Vc | Circular velocity |
| VCO | Voltage-controlled oscillator |
| VDC | Volts direct current |
| VGP | Vehicle ground point |
| VHF | Very high frequency |
| VHF/AM | Very high frequency/audio modulated |
| VM | Voltmeter or measured velocity |
| VO | Initial velocity |
| VOL | Volume |
| VOX | Voice-operated relay |
| VSWR | Voltage standing wave ratio |
| W/G | Water-glycol |
| WMS | Waste management system |
| WPM | Words per minute |
| WTR | Western test range |
| XC | Command module station |
| XCVR | Transceiver |
| XDUCER | Transducer |
| XFMR | Transformer |
| XMIT | Transmit |
| XMTR | Transmitter |
| XPONDER | Transponder |
| XS | Service module station |
| ZN | Zinc |
| DELTA/P | Differential pressure |
| DELTA/V | Differential velocity |