S/S may refer to:
- A Ship prefix that identifies a vessel as steam powered
- A common naming prefix for any Merchant vessel
- S/S, a medical abbreviation for Signs and symptoms
- In clothing, refers to short-sleeved (as opposed to L/S (long-sleeved))
- Solidification / Stabilization (S/S) with Cement, a method of management and reuse of contaminated waste.
abbr. same size