"A Microcontroller is single chip that contains not only a central processing unit but also memory and i/o ports,..."

Not necessarily.

As Erik has already said, this has been done to death SOooooooooooooooooooooo many times, and the same old chestnusts keep coming up over & again!

eg, Intel now use "microcontroller" as a marketing term just to mean a processor that they intend for embedded control applications - as opposed to the ones that they intend for computer applications: they "downgrade" processors to microcontrollers when they feel they're too old hat for computer applications.
Thus Intel now consider the 486, 386, etc to be "microcontrollers"