'agrestian' originates from Latin, specifically the word 'agrestis,' where 'ager' meant 'field' or 'land.'

'agrestis' transformed into the Medieval Latin word 'agrestianus,' and eventually became the modern English word 'agrestian.'

Initially, it meant 'pertaining to fields or land,' but over time it evolved into its current meaning of 'relating to the countryside or rural areas.'