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

See also: wary

• sadomasochism
• sadomasochist
• sadomasochistic
• sae
• Saek
• Safaqis
• Safar
• safari
• safari park
• xylene
• xylo-
• Xylocaine
• Xylocopa
• xylography
• xylol
• Xylomelum
• Xylomelum pyriforme
• xylophone
• xylophonist
• Xylopia
• Xylopia aethiopica
• xylose
• xylosma
• Xylosma congestum
• Xyphophorus