S4
- 4 (disambiguation)
- 4S (disambiguation)
- Alco S-4
- Andarine
- Audi S4
- Bremen S-Bahn
- Brussels Regional Express Network
- Carinthia S-Bahn
- County Route S4 (California)
- Form S-4
- Fourth heart sound
- Hanover S-Bahn
- Hibernation (computing)
- Hydra Technologies Ehécatl
- Karlsruhe Stadtbahn
- Lancia Delta S4
- Letov Š-4
- Nikon Coolpix S4
- P4 gauge
- Prussian S 4
- Rhine-Neckar S-Bahn
- Rostock S-Bahn
- S (disambiguation)
- S (programming language)
- S04
- S4 (Berlin)
- S4 (Munich)
- S4 (Nuremberg)
- S4 (RER Vaud)
- S4 (Rhine-Main S-Bahn)
- S4 (Rhine-Ruhr S-Bahn)
- S4 (St. Gallen S-Bahn)
- S4 (ZVV)
- S4 (classification)
- S4 (gamer)
- S4 (military)
- S4 (modal logic)
- S4 algebra
- SATA International
- SG2 Shareable (Fire Control) Software Suite (S4)
- SSSS (disambiguation)
- Sacral spinal nerve 4
- Salzburg S-Bahn
- Samsung Galaxy S4
- Samsung Galaxy S4 Mini
- Samsung Galaxy Tab S4
- Seibel S-4
- Shift4 Payments
- Stuttgart S-Bahn
- Supermarine S.4
- Tetrahedral symmetry
- Tetrasulfur
- Tyrol S-Bahn
- USS S-4 (SS-109)
- Upper Austria S-Bahn
- Vienna S-Bahn
- Vorarlberg S-Bahn