'accum' originates from the word 'accumulator', which is derived from the Latin word 'accumulare', where 'ad-' meant 'toward' and 'cumulare' meant 'to heap up'.

'accumulare' transformed into the English word 'accumulator', and eventually became the colloquial abbreviation 'accum'.

Initially, it meant 'to heap up or gather', but over time it evolved into its current meaning of 'a device for storing energy'.