What does "on guard" mean?

The starting position of a fencing bout.

What is a synonym for "on guard"?

Common synonyms include: alert, all ears, all eyes, argus-eyed, at bay, aux abois.

adj

adj ·Uncommon ·Advanced level

Adjective

1
The starting position of a fencing bout.
"We fall on guard, and after all it is a friend who comes to meet us."
2
Vigilant, alert.
3
Transmitting on the aircraft emergency frequency.

Adjective

"We fall on guard, and after all it is a friend who comes to meet us."