Offence is a central concept in impoliteness, aggression and conflict research, yet has received only passing mention in definitions of impoliteness and related concepts. Janicki (2017) argues that impoliteness and language aggression scholars are needlessly worried about definitions. We use Janicki’s (2017) work as a spring-board into a discussion of definitions of impolite or taboo language, airing potential problems and suggesting that the study of metalanguage offers at least a partial solution. We report a study of the metalanguage of OFFENCE in British English, and briefly examine whether there are any differences in Australian English, using SketchEngine to interrogate data in the two-billion word Oxford English Corpus. In so doing, we tease out different uses of the term offensive, and show that concepts such as OFFENCE are coloured by the specific linguistic and cultural contexts in which they appear. We conclude that while corpus-based metalinguistic analyses cannot completely eliminate the problem of definitional infinite regress, they do, however, offer an empirically grounded way of defining words that allows us to move beyond the intuitions of individual researchers.