'deep-seated' originates from the combination of 'deep' and 'seated', where 'deep' meant 'extending far down from the top or surface' and 'seated' meant 'fixed or established'.

'deep-seated' changed from the Old English word 'dēop' (deep) and 'geseted' (seated) and eventually became the modern English word 'deep-seated'.

Initially, it meant 'firmly established or fixed', and this meaning has largely remained the same in modern usage.