The meaning of the Acronym SI is...

SI is

• Solar Inertial
• Scientific Instrument
• International Systems of Units (ISU preferred)
• Center Support Operations (KSC Directorate)

More Meanings For SI:

• Source Index
• Signed Integer
• SoftImage Graphics
• Shift In
• Single Inheritance
• Standard Interface
• Socket Interface
• Semi Iterative
• Sub Indices
• Selectable Interface
• Slow Import
• Secure Internet
• Silly I
• Simply Irresistible
• Silicon

SI is also in:

• Assembly
• Chat
• Chemistry
• File Extensions
• General
• Networking
• Security