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

See also: wary

• you'd
• you'll
• you're
• you're welcome
• you've
• you-all
• you-drive
• young
• young bird
• young blood
• young buck
• young carnivore
• young fish
• young girl
• young lady
• young mammal
• young man
• young person
• Young Turk
• young woman
• Young's modulus
• young-bearing
• young-begetting
• younger
• youngish