well-entrenched
/ˌwɛlɪnˈtrɛn(t)ʃt/ /ˌwɛlɛnˈtrɛn(t)ʃt/adjective
1Of a military position or force: securely defended by a trench or trenches; well dug-in; (more generally) well-defended against attack.
2Firmly established; difficult to challenge or dislodge; (hence) unlikely to change.
- Originally as part of an extended metaphor.Now the more common sense..
Origin
Late 16th century; earliest use found in William Garrard (d. 1587). From well + entrenched.