1. Stock; race; family 
2. A race, or a fixed and permanent variety

Derived forms: stirpses

• family Spirochaetaceae
• family Spirulidae
• family Squalidae
• family Squatinidae
• family Squillidae
• family Staphylaceae
• family Staphylinidae
• family Steatornithidae
• family Stenopelmatidae
• family Stercorariidae
• family Sterculiaceae
• family Stichaeidae
• family Stizidae
• family Strelitziaceae
• family Streptomycetaceae
• family Strigidae
• family Stromateidae
• family Strombidae
• family Strophariaceae
• family Struthionidae
• family Sturnidae
• family Styracaceae
• family Suidae
• family Sulidae
• family Sylviidae