Deep-grounded

[…] as they have no root, no deep-grounded knowledge, no well-fixt principles, no regular light, but hasty gleams only; […]

Source: wiktionary

[…] for it is utterly impossible to sever by outward interference the threads of history, to force back again by some diplomatic mediation or other, deep-grounded antagonisms taken in the midst of their development.

Source: wiktionary

[…] the general policy has been guided by a deep-grounded recognition of the principles of justice and right on the part of both people; […]

Source: wiktionary

Instead of discipline and preparation for the task of the future, instead of deep-grounded experience in coöperative effort, we shall get, if strike-breakers and blind legislators and brutal policemen and prejudiced judges and visionless employers prevail, despair and hate and servile rebellions.

Source: wiktionary