Market Power in microeconomic theory What does the term Market Power mean in microeconomic theory
In competition policy (part of microeconomics), market power is often defined as the ability of a firm to raise and maintain prices above the levels that would prevail under competitive conditions (with obvious adjustments if the market power is held by a buyer).  Having market power does not necessarily mean it is used or abused, just that it can be

See for example:


https://stats.oecd.org/glossary/detail.asp?ID=3256
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/284400/oft415.pdf