'nonobservant' originates from the prefix 'non-' meaning 'not' and the word 'observant,' which comes from Latin 'observare,' meaning 'to watch over.'

'observant' changed from the Latin word 'observantem' and eventually became the modern English word 'observant.' The prefix 'non-' was added to form 'nonobservant.'

Initially, 'observant' meant 'to watch over,' but over time, 'nonobservant' evolved to mean 'not paying attention.'