I actually dislike the wikipedia definition. It suffers from the same general definitional problem: which market? Setting aside the above, the definition suff

I actually dislike the wikipedia definition. It suffers from the same general definitional problem: which market? Setting aside the above, the definition suffers for ignoring the question of why there are no viable substitutes. It's a dangerous omission since the implication, at least with respect to legal policy, is that it is the "fault" of the firm. The closest one could get to a useful definition of monopoly would be: a firm whose would-be competitors are coercively excluded from competing in the market. Of course even that still suffers from the subjectivity of defining the scope of "the market".