The use of a word in an incorrect way, for example the use of mitigate for militate.

‘English and American studies, especially, seemed to be focusing on narrative and drama in ways that excluded from study bizarre and interesting phenomena such as obsessive rhythm and catachresis.’
‘Its transformation seems more catachresis than irony, more a twisted similarity than an inversion or negation.’ (From OED:
In postcolonial theory, according to Bill Ashcroft and others, catachresis “is the process by which the colonized take and reinscribe something that exists traditionally as a feature of imperial culture, such as parliamentary democracy” (34) and either render it or transform it in relation to their own culture or politics. In other words, retrieving or articulating native histories of practices or concepts considered purely European, performs a productive catachresis and enables the colonized natives to imagine and articulate resitent modes of politics.