x-ray vision

Short definition from Wiktionary

Noun

1. 1
   Alternative spelling of X-ray vision.
2. 2
   Vision into the X-ray portion of the light spectrum, enabling visibility through certain solid matter.
3. 3
   The ability or superpower to see through most or all solid objects as if they were transparent.
4. 4
   A hack allowing players to see enemies behind walls or other solid objects.