S

Schutze : German rifleman
Schwere : German designation for heavy tank or vehicle
Schwerpunkt : primary area designated for combined arms attack where all branches coordinate their efforts to achieve a breakthrough( usually  against recoinoitered weak position in enemy line)

SD: Sicherheitsdienst (Security Service): was primarily the intelligence service of the SS and the NSDAP. The organization was the first Nazi Party intelligence organization to be established and was often considered a "sister organization" with the Gestapo, which the SS had infiltrated heavily after 1934. Between 1933 and 1939, the SD was administered as an independent SS office, after which it was transferred to the authority of the Reich Security Head Office (Reichssicherheitshauptamt, or RSHA), as one of its five offices.
Sd.Kfz. : Sonderkraftfahrzeug (abbreviated Sd.Kfz.) is German for special purpose vehicle (or Special Ordnance Vehicle). It was for example used by Nazi Germany during World War II, to represent armoured fighting vehicles, for example Sd.Kfz.101 for the Panzer I. For a complete list on WaT: LINK (http://www.warandtactics.com/smf/index.php?topic=200.msg307#msg307)

Sierra : S in NATO alphabet

SLBM: submarine-launched ballistic missiles

Sonderaktion 1005: The Sonderaktion 1005, also called Aktion 1005, or Enterdungsaktion ("Exhumation action") was an operation conducted by Nazi Germany during the Second World War, the aim of which was to hide traces of mass murder conducted by German forces during Aktion Reinhard. Conducted in strict secrecy during 1942-1944, it made use of prisoners from concentration camps, Jews, or men from neighbouring areas. Workers in this capacity were officially called Leichenkommando ("corpse units"); they were often put in chains in order to prevent escape. The Aktion was overseen by Sonderkommando 1005, along with squads of the Sicherheitsdienst and Ordnungspolizei.

SPA: Self Propelled Artillery. Any artillery gun that is on some kind of a vehicle mount making it mobile
Spalling: When a projectile strikes the hard armour of an AFV it can cause the armour to break apart. The shock generates enough force to knock off pieces of the armour inside the target vehicle. This effect is known as spalling. The spalling becomes projectiles on the inside of the vehicle creating crew casualties
Splittergranate : German for High Explosive round

SRBM: short-range ballistic missile

SS : Schutzstaffel. Started as Hitlers bodyguard and during the course of the war grew to a large seperate army within the reich next to the Wehrmacht.
SSG: Staff Sergeant
SSM: surface-surface-missile
SSTV : SS Totenkopfverbande. freely tanslated SS Deadshead organisation.
This was the pre-war SS unit lead by Theodor Eicke, they were mainly responsible for the concentrationcamps, guarding and organisation. After 1939 they completely transformed into the 3rd SS Totenkopf division.

Stab : German for Headquarters
Stabskompanie : headquarters company
Strategy:
A Strategy is a long term plan of action designed to achieve a particular goal, most often "winning." Strategy is differentiated from tactics or immediate actions with resources at hand by its nature of being extensively premeditated, and often practically rehearsed. Strategies are used to make the problem easier to understand and solve.
The word derives from the Greek word strat?gos, which derives from two words: stratos (army) and ago (ancient Greek for leading). Strat?gos referred to a 'military commander' during the age of Athenian Democracy.
Stuetzpunkt : defensive position prepared for all round defense
Sturmgeschutz : German assault gun (like Stug III)
Sturmhaubitze : German self propelled artillery (like Stuh 42)

SNAFUBAR - Situation Normal: All Fucked Up Beyond All Repair/Recognition/Reason
SOL- Shit Out of Luck
SRDH- Shit Rolls Down Hills
SSDD- Same Shit, Different Day
SSDWI- Shit Sucks, Deal With It
SUSFU- Situation Unchanged, Still Fucked Up

SSN: Attack Submarine (nuclear)
SC: Cruiser Submarine
SF: Fleet Submarine
SLBM: Submarine-launched ballistic missiles
SM: Mine Laying Submarine
SP: Scout (Section) Patrol Craft (used during WWI)
SS: Submarine
SSA: Cargo Submarine
SSBN: US Navy ballistic missile submarine / Fleet Ballistic Missile Submarine
SSG: Guided Missile Submarine
SSGN: US Navy cruise missile submarine
SSK: Anti-submarine Submarine
SSO: Oiler Submarine
SSP: Transport Submarine
SSR: Radar Picket Submarine
SSRN: Radar Picket Submarine (nuclear)