Nitpick: legally a monopoly doesn't require zero competitors.

> Legally

Only when getting fined for antitrust or monopolistic behavior, which doesn't mean it is a monopoly - only that a regulating body is trying to prevent it from eventually becoming one.

Definitively, mono-poly means one entity in the market.

I understand the etymology, however using that as a basis for reasoning is unhelpful since it's the legal and economic consequences in real-life that actually mean something.