'lawfulness' originates from the Old English word 'lagu', meaning 'law', combined with the suffix '-ful', indicating 'full of', and '-ness', denoting a state or condition.

'lagu' transformed into the Middle English word 'lawe', and eventually became the modern English word 'law'.

Initially, it meant 'full of law', but over time it evolved into its current meaning of 'being in accordance with the law'.