opposed to or regulating trusts; specif., designating or of federal laws, suits, etc. designed to prevent restraints on trade, as by business monopolies, cartels, etc.
See antitrust in American Heritage Dictionary 4
(ănˌtē-trŭstˈ, ănˌtī-)
adjective
Opposing or intended to regulate business monopolies, such as trusts or cartels, especially in the interest of promoting competition: antitrust legislation.