entrench

(construction, archaeology) To dig or excavate a trench; to trench.

(military) To surround or provide with a trench, especially for defense; to dig in.

(figuratively) To establish a substantial position in business, politics, etc.

To invade; to encroach; to infringe or trespass; to enter on, and take possession of, that which belongs to another; usually followed by on or upon.

To cut in; to furrow; to make trenches in or upon.

(figuratively) To become completely absorbed in and fully accept one's beliefs, even in the face of evidence against it and refusing to be reasoned with.