In his case it's the ability to hear a musical note and know what the note was.
Absolute pitch, or "perfect pitch", is the ability to perceive and comprehend musical sound as though it were language. "Naming notes" is the most recognizable effect of this perception.
Sphinx just about has it in one there. Of course, you can only name the note if you can read music in the first place. Likewise, it also means when you see a written note, you can sing it right on key.
This beggars the questions, of course, as to whether someone who can't read music can still have perfect pitch.