""Monopoly" generally incorporates the notion of single seller of some good. "
No. It's far more complex than this, that is the simplistic approach. Often people say "monopoly" when they really mean "dominant position", and its abuse.
Even Standard Oil didn't have full monopoly - but it vastly abused its dominant position for its own advantage. Nor Microsoft was the only seller of OS or computer software, but it was abusing its desktop software dominance.
Also, a monopoly/dominant position doesn't need to be unfair to customers buying goods - it can simple be unfair to any kind of competition, still resulting in economic damages (i.e. less jobs, less tax incomes, less innovation, etc. etc.)
Biting the hand that feeds IT
