Recent years have witnessed a growing trend towards regulating disinformation, particularly online disinformation. Regulatory efforts in this regard are especially prominent at the European Union level. This is the case even though there is currently no ‘European’ legal definition of disinformation. The European Union has thus effectively leapfrogged the foundational question of what precisely distinguishes disinformation from other forms of semantic content and proceeded to make policy decisions on how to regulate it, thereby running a real risk of undermining freedom of expression on the Internet. Drawing on relevant literature, primarily at the intersection of linguistics, the philosophy of language and law, this article argues that, in order to effectively discriminate it from other forms of semantic content that may legitimately fall within the protective scope of freedom of expression, disinformation should be legally defined as misleading information that is communicated with intent to mislead and that may cause harm.