| MLS | Microwave Landing System |
| ILS | Instrument Landing System |
| AVS | Advanced Vertical and short take-off and landing System [engl.] Flugzeugkonzept |
| LZ | Landing Zone |
| LCT | Landing Craft Tanks |
| HTOL | Horizontal Take-off and Landing [engl.] Konventionelles Flugverfahren |
| BLC | Beam Landing Correction [engl.] |
| BLEU | Blind Landing Experimental Unit [engl.] Erprobungsträger zum Blindlanden |
| M/W | Microwave |
| MCI | Microwave Communications Incorporated |
| MWFT | Microwave Fourier Transform |
| MIP | Microwave-Induced Plasma |
| LFMA | Low-Field Microwave Absorption |
| MED | Microwave plasma Emission Detector |
| LMDR | Laser Microwave Double Resonance |
| FT-MW | Fourier Transform Microwave Spectroscopy |
| MMMA | Magnetically Modulated Microwave Absorption |
| MODR | Microwave-Optical Double Resonance |
| CMP | Capacity-coupled Microwave Plasma |
| MMIC | Monolithic Microwave Integrated Circuit |
| WMAP | Wilkinson Microwave Anisotropy Probe |
| WiMAX | Worldwide Interoperability for Microwave Access |
| MMR | [magnetically-]Modulated Microwave Reflection |
| MASER | Microwave Amplification by Stimulated Emission of Radiation |
| V4FSL | System V Release 4 File System Layout |
| ES-IS | End System to Intermediate System Protocol [OSI] |
| FSS | Fast System Switch [System V] |
| ISIS | Intermediate System to Intermediate System Protocol [OSI] |
| PS | Personal System [IBM] |
| SS7 | Signalling System No. 7 |
| FS | Floppy System |
| FS | File System |
| QMS | Qualitätsmanagement-System |
| SVR4 | System V Release 4 |
| SP | System Program |
| IS-IS | Intermediate System to Intermediate System |
| ISPLSI | in-system-programmable LSI |
| ISH | Intermediate System Hello |
| RS | RISC System |
| SI | System Information |
| SIP | System-in-Package |
| JCS | Job Control System |
| COSY | Conferencing System |
| ICS | IBM Cabling System |
| JMS | Job Management System |
| SMB | System Management Bus |
| HS | Harmonisiertes System |
| SOC | System On a Chip |
| HBS | Home Bus System |
| KES | Key Escrow System |