South Sea Imports (quilt distributor; Rancho Dominguez, CA)
Software and Systems Integration
Spectral Solar Irradiance (sunlight)
Security Services International (Delaware)
Student Success Initiative
ShipConstructor Software, Inc. (Canada)
Saint Simons Island (place name in Georgia, USA)
Soil Structure Interaction
Semaine de la Solidarité Internationale (French: International Solidarity Week)
Sawtooth Software, Inc. (Orem, UT)
Solid-State Imager
Sales Satisfaction Index
Strålskyddsinstitutet
Spatial Sciences Institute
Southern States Insurance (various locations)
Speculative Sentiment Index (Forex Capital Markets investment tool)
Système de Sécurité Incendie (French: Fire Safety System)
Sliding Scale Insulin
Storage Strategies, Inc. (Springfield, VA)
Standing Settlement Instruction
Society of Scribes and Illuminators (UK)
Sight Savers International
Semi-Structured Interview (various organizations)
Sharp Semiconductor Indonesia
Solid State Interlocking
Saturn Saab Isuzu (cars)
Society of Socio-Informatics (Japan)
Storage Service Interface (software)
Solid-Solid Interface (chemical engineering)
School Safety Initiative (various organizations)
Social Science Index (journal)
Single Sign-In (authentication)
Severe Speech Impairment
Saigon Securities, Inc. (Vietnam)
Studies in Symbolic Interaction (sociology)
Serenity Systems International (Lewisville, TX)
Serial Synchronous Interface
Size-Selective Inlet
Signal Strength Indicator
Silent Spring Institute
Service Support Internet (Austria)
Soldier Support Institute
Stakeholder Satisfaction Index (education)
Spaceport Systems International
State Sanitary Inspectorate (health; various locations)
Sino Strategic International (Australia)
Ship Station Identification
Short-Circuited Stub Inductor
Standard Settlement Instruction
Scuola Superiore ISUFI (Istituto Superiore Universitario di Formazione Interdisciplinare; Italian: University Institute of Interdisciplinary Education Superior School)
