Select the most appropriate synonym of the given word.

ENTRENCH 

Firmly established

The most appropriate synonym of the word "entrench" is firmly established.

• Entrench means to establish (something) firmly or deeply.
• Firmly established means established in a secure or lasting way.
• Inefficacy means lack of effectiveness.
• Extensive means having a wide range or scope.
• Eccentricity means the quality of being unconventional or odd.