deep-rooted

Of a plant, having deep roots.

He observed the leaves of trees there abouts more deeply green then else∣where, the Oakes broad-spreading, but not deep-rooted;

1726, Jonathan Swift (translator), “Horace, Book I, Ode XIV” in Miscellanies in Prose and Verse, London: T. Woodward and Charles Davis, 1736, Volume 5, p. 193, Poor floating Isle, tost on ill Fortune’s Waves, Ordain’d by Fate to be the Land of Slaves; Shall moving Delos now deep-rooted stand, Thou, fixt of old, be now the moving Land?

Of a non-living object, deeply and firmly embedded (in the ground, etc.)

Firmly established in thought or behavior and difficult to change.

They avoid conflict at all costs because of their deep-rooted fear of upsetting people.

[…] Temporarie faith keeping residence only in the out-face of the heart, is ouerswayed & ouerborn in temptation by euery strong desire, or deep-rooted passion.