1. Vitally important
   - life-and-death

See also: crucial, important

• South Sea Islands
• south side
• south southwest
• South Temperate Zone
• South Vietnam
• South West Africa
• south wind
• South Yorkshire
• South-African yellowwood
• south-central
• South-Central Dravidian
• south-polar
• south-seeking pole
• south-southeast
• Southampton
• southbound
• Southdown
• southeast
• Southeast Asia
• southeast by east
• southeast by south
• southeaster
• southeasterly
• southeastern
• southeastern pocket gopher