'electroencephalogram' originates from Greek, specifically the words 'elektron' meaning 'amber' (related to electricity) and 'enkephalos' meaning 'brain', combined with 'gramma' meaning 'something written'.

'electroencephalogram' was derived from the German word 'Elektroenzephalogramm' and eventually became the modern English word 'electroencephalogram'.

Initially, it meant 'a written record of brain activity', and this meaning has largely remained the same in modern usage.