'overreactor' originates from the English word 'overreact,' where 'over-' meant 'excessively' and 'react' meant 'to respond to a stimulus.'

'overreact' changed from the English word 'react' with the prefix 'over-' added to indicate excessive reaction, eventually forming 'overreactor' to describe a person who overreacts.

Initially, it meant 'to respond excessively,' and this meaning has largely remained the same in modern usage.