The meaning of the Acronym FOS is...

FOS is

• Full of stool (constipated)

More Meanings For FOS:

• Freak Out Squad
• Forensic and Osteoarchaeological Services
• Fructo-OligoSaccharide
• Free Online Scholarship
• Full Of Shit
• Fantastically Oaky Stuff
• Finkel Osteogenic Sarcoma
• Friend Of Sauce
• Full Order Scan
• Ferry Operators Service
• Fortress Of Solitude
• The Fisheries Operation System
• Feat Of Strength
• Four Owners Share
• The Friends Of Stern

FOS is also in:

• Adults
• Botany
• Chat
• Chemistry
• Funnies
• Unfiled
• Universities