1. Vigilant
   "must remain on your guard in such a situation"
   - on guard, on one's guard, upon one's guard

See also: wary

• bestiary
• bestill
• bestir
• bestir oneself
• bestow
• bestowal
• bestower
• bestowment
• bestrew
• bestride
• bestseller
• bestubbled
• besuited
• bet
• bet on
• beta
• beta blocker
• beta blocker eyedrop
• beta cell
• Beta Centauri
• Beta Crucis
• beta decay
• beta endorphin
• beta globulin
• beta iron