SAAF – South African air Force
SAC – Senior Aircraftman
SACEUR – Supreme Allied Commander Europe
SACW – Senior Aircraftwoman

SAFO – Senior Air Force Officer

SAOEU – Strike Aircraft Operational Evaluation Unit
SAN – School of Air Navigation
SAP – School of Air Pilotage
SAR – Search And Rescue
SAR – Sanostacna Aeroplansva Radionica, (Independent Aviation Workshop)
SARD – Southern Aircraft Repair Depot
SARTU/S – Search and Rescue Training Unit/Squadron
SAS – Servicing Aircraft Section
SASO – Senior Air Staff Officer
SATC – School of Air traffic Control

Satt – Satellite
SBA – Standard Beam Approach
S/C Sergeant Chef
SC – Salvage Centre / Support Command / Strike Command
SCBS – Strike Command Bombing School
SCCS – Strike Command Communication Squadron
SCDU – Strike Command Development Unit
SCF – Squadron Conversion Flight
"Schooly" or "Schoolie" – Education Officer

"Scrambled Egg" – Oak leaf decoration on the peal of a senior officer's cap

"Screaming Downhill "– Executing a power dive

"(to) Scrub" – To wash out or Abort

SCR – School of Control & Reporting
SCS – Southern Communication Squadron/Special Communication Squadron
SCSR – School of Combat Survival and Rescue

SCU – Servicing Command Unit

SD – Special Duty / Special Duties / Stores Depot
SD155. – Operational Memorandum
SDF – Special Duties Flight
SD(R)DU – Special Duties (Radio) Development Unit
SDU – Signals Development Unit
SEAAC – South East Asia Air Command
SEAC – South East Asia Command
SEACF – South Eastern Area Communication Flight
SEAFIS – South Eastern Area Flying Instructors School
SEASI – South Eastern Area School of Instruction
"Second Dickey" – Second pilot

SEF – Special Experimental Flight
SEP – Special Erection Party

SF – Station Flight
SFC – School of Flying Control
SFCS – Squadron & Flight Commanders School
SFF – Service Ferry Flight / Special Forces Flight
(S)FPP – (Service) Ferry Pilots Pool
SFT – School of Flying Training
SFTS – Service Flying Training School
SFU – Signal Flying Unit
Sgt – Sergeant
SGR – School of General Reconnaissance
SGR&AN – School of General Reconnaissance & Air Navigation (India)
SHAEF – Supreme Headquarters Allied Expeditionary Force
"Shaken" – To be suddenly taken aback

"Shaky Do" – A dangerous operation or Event

"Shagging" – Making love

SHAPE – Supreme Headquarters Allied Powers Europe

"She a night-fighter" or "That's where the night-fighter's were" – Night-fighters were "prostitutes"

"Shooting A Line" – Exaggerated talk, generally about ones own abilities

"Show Down In Flames" – Crossed in love or Severely reprimanded

"Show" -good/poor/bad – Anything can be a "show" - a dinner party, outing, operation

SHQ – Station Head Quarters
SIC – Signals Intelligence Unit

"Sicky Dog" – To feel ill

SIF – Special Instruction Flight
SIF/U – Special Installation Flight/Unit
Sigs – Signals
SITF – Station Instrument Training Flight
SIU – Signals Intelligence Unit
SIS – Secret Intelligence Service
S/L or S/Ldr or SQN LDR – Squadron Leader
SLAIS – Specialised Low Attack Instructors School
SLAW – School of Land/Air Warfare
"Snake About" – Operational aerobatics

SMO – Senior Medical Officer

SMR – School of Maritime Reconnaissance

SN–2 – German night fighter radar
SNC – School of Naval Cooperation
SNCO – Senior Non-Commissioned Officer

"Snowdrop" – RAF Police

SO – Senior Officer / Section Officer

S of A – School of Administration

SoAC – School of Army Co–operation / School of Airfield Construction

SoAE – School of Aeronautical Engineering

SoAF – School of Air Fighting
SoAG – School of Air Gunnery

SoAF&G – School of Air Fighting and Gunnery
SOAF – Sultan of Oman's Air Force

SOAF&BD – School of Air Fighting & Bomb Dropping
SoAFTT(1) – School of Air Force Technical Training (India)
SoAG – School of Air Gunnery
SoAN – School of Air Navigation

SoAN&BD – School of Aerial Navigation & Bomb Dropping
SoAP – School of Air Pilotage

SoASR – School of Air Sea Rescue
SoAS – School of Sir Support
SoAT – School of Air Transport
SoATC – School of Air Traffic Control
SoC – School of Catering

SOC – Struck off Charge
SoCSR – School of Combat Survival and Rescue

SOE – Special Operations executive
SOF – Special Operations Flight
SoFC – School of Fighter Control / School of Ferry Control

SoFP – School of Fighter Plotting
SoGR – School of General Reconnaissance

SoJSPT – School of Jungle Self Preservation Training

SoLAW – School of Land/Air Warfare

SoI – School of Instruction

SOM – School of Music

SoMR – School of Maritime Reconnaissance
SoN&BD – School of Navigation & Bomb Dropping
SoNC&AN – School of Naval Cooperation & Aerial

                      Navigation
SoMA – School of Military Aeronautics
SoP – School of Photography

SoPT – School of Parachute Training

SoRF - School of Refresher Flying

SoRT – School of Recruit Training
SoSF – School of Special Flying

SoTT  or STT – School of Technical Training 
SoWT – School of Wireless Telephony
(SP) – Special Duties Officer

SP – Staging Post / Service Police
SPTU – Staff Pilots Training Unit
"Spun In" – Any bad mistake

"Sprog" – Brand new in uniform

                    - newly commissioned officer

"Squaff" – Squadron Officers (WAAF

Sq or Sqn or Sqd – Squadron
Sq O – Squadron Officer

SRAF – Southern Rhodesian Air Force
SRCU – Short Range Conversion Unit
SRF – School of Refresher Flying/Sea Rescue Flight/Search& Rescue Flight
SRTS – Short Range Transport Squadron
SRTU – Survival& Rescue Training Unit
SRU – Strategic Reconnaissance Unit
SRW – Strategic Reconnaissance Wing
S/S – Staff Sergeant
SS – Signals School/Salvage Section
SSC – Senior Supervisor's Course (for senior QGI's, conducted at
ACCGS – similar to regular Flying Supervisors Course)
SSF – Special Service Flight/Special Survey Flight
SSQ – Station Sick Quarters
SSTT – Supplementary School of Technical Training
SSU – Sentry Standards Unit
SSVAF – Straight Settlement Volunteer Air Force
STC – Strike Command

STDU – Synthetic Training development Unit
STF – Seaplane Training Flight/Special Training Flight
"Stooge" – A sind-in, a deputy, anyone who does something for someone else

"Stooging About" – Patrolling, flying slowly over an area, usually looking for trouble

STS – Seaplane Training Squadron/Special Transport Flight
STT or SofTT – School of Technical Training 

S&TT – Station & Target Towing
SU – Support Unit / Servicing Unit
SupO – Supply Officer

SWAFIS – South Western Areas Flying Instructors School
SWTS – Supplementary Wireless Telegraphy School
SWO – Station Warrant Officer
SWUAS – South Wales University Air Squadron