Radical
Stare

Mnemonic

You stand frozen in place the moment you see a ghost drift past the window. You can't move, can't blink—all you can do is stare. Standing rooted to the spot, seeing the impossible, your wide eyes refuse to look away.
Additional thoughts
Standing still + seeing intently = staring. Picture yourself upright and locked in place, eyes fixed on something shocking. The combination of a rigid, standing posture with intense seeing naturally produces a stare.
Quick recall
Stand still, see something impossible, and all you can do is stare.