'heedlessness' originates from the Old English word 'hēdan,' meaning 'to take care of,' combined with the suffix '-less,' indicating absence, and '-ness,' forming a noun.

'heedless' changed from the Old English word 'hēdan' and eventually became the modern English word 'heedless.'

Initially, it meant 'without care or attention,' and this meaning has largely remained the same in modern usage.