SSA
- Anti-SSA/Ro autoantibodies
- C0 and C1 control codes
- Gillespie algorithm
- Order of the Star of South Africa
- SSA Global Technologies
- Sainsbury's Staff Association
- Salvador Bahia Airport
- Same-sex attraction
- Sarva Shiksha Abhiyan
- Saudi Space Agency
- Schonfeld Strategic Advisors
- School of Saint Anthony
- Scottish Socialist Alliance
- Secular Student Alliance
- Seismological Society of America
- Selective Service Act of 1917
- Self-sampling assumption
- Semantic structure analysis
- Senile systemic amyloidosis
- Senior Special Assistant
- Serial Storage Architecture
- Serious Sam Advance
- Sessile serrated adenoma
- Shady Side Academy
- Shan State Army
- Shared services agreement
- Shipconstructors' and Shipwrights' Association
- Side-side-angle
- Singapore Scout Association
- Singular Spectrum Analysis
- Slippery slope argument
- Slovak Society of Actuaries
- Soaring Society of America
- Social Security Administration
- Social Security Agency (Northern Ireland)
- Society for the Study of Addiction
- Society of Scottish Artists
- Software Security Assurance
- Space Situational Awareness Programme
- Special Agent
- Special Service Agreement
- Special somatic afferent
- Specific surface area
- State Security Agency (South Africa)
- Static single-assignment form
- Stationary Subspace Analysis
- Steamship Authority
- Strong subadditivity of quantum entropy
- Sub-Saharan Africa
- SubStation Alpha
- Sudan Studies Association
- Sulfosalicylic acid
- Super systolic array
- Swedish Society of Radio Amateurs
- WWI
- Woodrow Wilson