'slovenliness' originates from English, specifically formed from the adjective 'slovenly' with the nominalizing suffix '-ness'; 'slovenly' in turn derives from the noun 'sloven'.

'sloven' appeared in Middle English (from late medieval sources) and is believed to have cognates in Middle Dutch and Middle Low German meaning 'slack' or 'careless'; from 'sloven' came the adjective 'slovenly' and later the noun 'slovenliness'.

Initially it referred to 'a sloven' (an untidy or careless person) or the quality of being slack; over time it evolved into the current meaning 'the state or quality of being slovenly; untidiness or carelessness'.