Answer:
The term Grey Goo or Gray Goo was coined by an American Engineer, Kim Eric Drexler. The term was coined by him in his book - Engines of Creation (1986).
The term Grey Goo is a hypothesis or a theory offered by Drexler. It means the end of the world by tiny machines. According to the theory there will be nanotechnological engines which can replicate themselves to clean up the environment. Drexler termed them Universal Assemblers or Nanobots. If these machines went out of control, multiplied in excess and started consuming everything to support the process, they would turn the planet into grey goo.
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