crook [ME] A crook was originally a hooked tool or weapon. The source is Old Norse krokr ‘hook’. The word was used to mean ‘dishonest, crooked piece of conduct’ in medieval English, and although this sense seems to have fallen from the record by the 17th century, it reappeared used for villains in late 19th-century America. In Australia and New Zealand crook has meant ‘bad, unpleasant’, ‘dishonest, unscrupulous’, and ‘ill, unwell’ since the late 1890s. These uses might come from the old British thieves’ slang sense ‘stolen’.