i Register
In some senses, deep-seated is marked as figuratively. Watch for register when choosing this word.
adj
Physically located at a deep level.
a deep-seated tumour
Weaknesses in the earth’s crust allow deep-seated heat to rise nearer to the surface.
Firmly implanted or established in thought or behavior and difficult to change; deeply ingrained.
She has a deep-seated belief in the essential goodness of human nature.
[…] instead of the bright beams that used to play in those eyes, there was now a dark deep-seated sorrow, almost despair.