'deeply-rooted' originates from the combination of 'deeply' and 'rooted', where 'deeply' means 'to a great depth' and 'rooted' means 'established firmly'.

'deeply-rooted' evolved from the Old English word 'rōtian', meaning 'to root', combined with 'deeply' to emphasize the extent of establishment.

Initially, it meant 'having roots that go deep into the ground', but over time it evolved into its current metaphorical meaning of 'firmly established'.