(1):
(v. i.) 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; as, the king was charged with intrenching on the rights of the nobles, and the nobles were accused of intrenching on the prerogative of the crown.
(2):
(v. t.) To cut in; to furrow; to make trenches in or upon.
(3):
(v. t.) To surround with a trench or with intrenchments, as in fortification; to fortify with a ditch and parapet; as, the army intrenched their camp, or intrenched itself.