- s – second(s)
- S&W – Smith & Wesson
- SABCA – Société Anonyme Belge de Constructions Aéronautiques
- SABR – Selectable Assault Battle Rifle
- SABS – Stabilizing Automatic Bomb Sight
- SAC – Small Arms Collimator
- SACLOS – Semi-Automatic Command to Line Of Sight
- SADA – Standard Advanced Dewar Assembly
- SADARM – Sense And Destroy Armor (US)
- SADF – South African Defence Force
- SAE – Society of Automotive Engineers
- SAF – Small Arms Fire
- SAFCS – Small Arms Fire Control System
- SAFIRE – Surface-to-Air Fire
- SAL – semi-active laser
- SAM – surface-to-air missile
- SAMM – Société d'Applications des Machines Motrices
- SANDF – South African National Defence Force
- SANG – Saudi Arabian National Guard
- SAP – Semi-Armour-Piercing
- SAPHEI – Semi-Armour-Piercing High Explosive Incendiary
- SAPI – semi-armour-piercing incendiary
- SAS-EAS – Sealed Authenticator System - Emergency Action Procedures (Nuclear Weapons Release Control)
- SASR – Special Application Sniper Rifle
- SAT – Small Arms Trainer
- SATCP – Systиme Anti-aérien à Trиs Courte Portée (very short-range anti-aircraft system)
- SAVA – Standard Army Vectronics Architecture
- SAW – Squad Automatic Weapon
- SAWS – Squad Automatic Weapon System
- SB – Short Barrel
- SCORE – Stratified Charge Omnivorous Rotary Engine
- SD – self-destruct(ion)
- SEAL – Sea/Air/Land
- SEALOCK – Search, Locate, and Communicate or Kill
- SEATO – Southeast Asia Treaty Organisation
- SEME – School of Electrical and Mechanical Engineering
- SEN – shell extended range NORICUM
- SEP – Soldier Enhancement Programme
- SFCS – Simplified Fire-Control System
- SFIM – Société de Fabrication d'Instrument de Mesure
- SFIRR – solid fuel integral rocket/ramjet
- SFM – Sensor Fuzed Munitions
- SFMG – Sustained Fire Machine Gun
- SFSW – Special Forces Support Weapon
- SFW – Special Forces Weapon
- SGTS – Second-Generation Tank Sight
- SH/PRAC – squash head practice
- SHORAD – Short-Range Air Defence System
- shp – shaft horsepower
- SIC – Second in Command
- SICPS – Standard Integrated Command Post Systems
- SINCGARS – Single Channel Ground/Air Radio System
- SIP – System Improvement Plan/Programme
- SIPS – Small Integrated Propulsion System
- SJFN – Semi-Jacketed Flat Nose
- SJHP – Semi-Jacketed Hollow Point
- SKOT – Sredni Kolowy Opancerzny Transporter (armoured personnel carrier)
- SLAP – saboted light armor penetrator
- SLAW – Shoulder-Launched Assault Weapon
- SLEP – Service Life Extension Program (US)
- SLR – Self-Loading Rifle
- SLR – Super Low Recoil
- SLWAGL – Super Light Weight Automatic Grenade Launcher
- SM – smoke
- SMAW – Shoulder-launched Multi-purpose Assault Weapon
- SMG – sub-machine gun
- SMK – Smoke
- Smoke – BE smoke base ejection
- Smoke – WP smoke white phosphorus
- SMP – Surface Mine Plough
- SNAFU – Situation Normal, All Fouled Up
- SNCO – Staff Non-Commissioned Officer (USMC, E-6 - E-9)
- SNCOIC – Staff Non-Commissioned Officer In Charge (USMC)
- SOCOM – Special Operations Command
- SOF – Special Operations Force(s)
- SOG – Speed Over Ground
- SOP – Standing/Standard Operational Procedure(s)
- SP – Shore Patrol
- SP – self-propelled
- SP – Soft Point
- SPAAG – self-propelled anti-aircraft gun
- SPAAM – self-propelled anti-aircraft missile
- SPAG – self-propelled assault gun
- SPARK – solid propellant advanced ramjet kinetic energy missile
- SPAS – Special Purpose Automatic Shotgun
- SPATG – self-propelled anti-tank gun
- SPAW – self-propelled artillery weapon
- SPG – self-propelled gun
- SPH – self-propelled howitzer
- SPL – self-propelled launcher
- SPLL – Self-propelled Loader Launcher
- SPM – self-propelled mortar
- SPP – Special Purpose Pistol
- SPR – Special Purpose Rifle
- SPS – Standard Positioning Service
- SPSM – Sensorgezundete Panzerabwehr SubMunition
- SPW – Special Purpose Weapon
- SR – Short Rifle
- SR – Staff Requirement
- SRAW – Short Range Assault Weapon
- SRC – Space Research Corporation
- SRG – shell replenishment gear
- SRI – Short Range Insert
- SRTS – Short Range Thermal Sight
- SRU – Shop Replaceable Unit
- SRU – Slip Ring Unit
- SRV – Surrogate Research Vehicle (US)
- SSA – Special Spaced Armour
- SSG – Single Shot Gun
- SSK – Single Shot Kill
- SSW – Squad Support Weapon
- ST – Staff Target
- STA – shell transfer arm
- STAB – Steered Agile Beams
- STAFF – Small Target Activated Fire-and-Forget (US)
- STANAG – STANdardisation Agreement
- STARTLE – Surveillance and Target Acquisition Radar for Tank Location and Engagement (US)
- STE/ICE – Simplified Test Equipment/Internal Combustion Engine (US)
- STOVL – Short Take Off and Vertical Landing
- STUP – spinning tubular projectile
- SUB – SUBstitute
- SUC – Square Ultra Compact
- SUIT – Sight Unit Infantry Trilux
- SUSAT – Sight Unit Small Arms Trilux
- SWARM – Stabilised Weapon and Reconnaissance Mount
- SWAT – Special Weapons And Tactics
- SWC – Semi WadCutter
- SWS – Sniper Weapon System
Read more about this topic: Glossary Of Military Abbreviations