If you have a problem with people using the word monopoly as synonymous with anti-trust then just interpret it as anti-trust and ignore the word.
For example, Article 102 of the Treaty on the Functioning:
Any abuse by one or more undertakings of a dominant position within the internal market or in a substantial part of it shall be prohibited as incompatible with the internal market in so far as it may affect trade between Member States. Such abuse may, in particular, consist in: (a) directly or indirectly imposing unfair purchase or selling prices or other unfair trading conditions; (b) limiting production, markets or technical development to the prejudice of consumers;
With Sherman Antitrust Act of 1890 we get supreme court cases that states things like: The purpose of the [Sherman] Act is not to protect businesses from the working of the market; it is to protect the public from the failure of the market. The law directs itself not against conduct which is competitive, even severely so, but against conduct which unfairly tends to destroy competition itself.
And in an other supreme court case:
The goal was to prevent restraints of free competition in business and commercial transactions which tended to restrict production, raise prices, or otherwise control the market to the detriment of purchasers or consumers of goods and services, all of which had come to be regarded as a special form of public injury. For that reason the phrase "restraint of trade," which, as will presently appear, had a well understood meaning in common law, was made the means of defining the activities prohibited.
Not a word about monopoly but a lot about behavior which in common speech people call monopoly but actually refer to behavior which is illegal according to anti-trust.