"Any sufficiently advanced technology is indistinguishable from a completely ad-hoc plot device"
Phlebotinum
* or Phlebotinium, for our Commonwealth brethren
is the versatile substance that may be rubbed on almost anything to cause an effect needed by a plot.
Some examples: nanotechnology, magic crystal emanations, pixie dust, a
sonic screwdriver, or even just some
Green Rocks. In essence, it is the stuff that makes the plot go. Without it, the story would grind to an abrupt halt. It's science, it's magic, it's strange things unknown to science or magic. The reader does not know how Phlebotinum would work and the creators hope he or she doesn't care.
CSI: Crime Scene Investigation and its spinoffs come with phlebotinum by the liter. Their favorite kind appears to be Luminol, the substance that reveals traces of blood. Luminol is real, though it's not nearly as convenient as it is on TV.
* For one, it's easily confused. Urine, feces, bleach, copper, animal blood and
horseradish all glow the same as human blood will.
According to
Joss Whedon, during the DVD commentary for the pilot episode of
Buffy the Vampire Slayer, the term "phlebotinum" originates from
Buffy writer (and
Angel co-creator) David Greenwalt's sudden outburst, "Don't touch the phlebotinum!" apropos of nothing.
* Whether or not he had the etymological connection in mind, "phlebotomy" is the drawing of blood. Ironically appropriate in context.
If the phlebotinum in question is simply a physical substance with unusual/extreme properties you are almost certainly dealing with the element
Unobtainium.
A.K.A. Handwavium. Compare
MacGuffin,
A Wizard Did It,
Hand Wave, and
Deus ex Machina.
Tropes
Applied Phlebotinum is among the
Tropes of Legend.