1. Vigilant
   - on guard, on one's guard, on your guard

See also: wary

• Vipera
• Vipera aspis
• Vipera berus
• Viperidae
• viperine
• viperine grass snake
• viperous
• Viracept
• viraemia
• virago
• viral
• viral delivery vector
• viral haemorrhagic fever
• viral hemorrhagic fever
• viral hepatitis
• viral infection
• viral pneumonia
• Viramune
• Virazole
• Virchow
• virement
• viremia
• vireo
• Vireo olivaceous
• Vireo solitarius