Definition of "entrench" [en•trench]

• To provide with a trench, especially for the purpose of fortifying or defending. (verb-transitive)
• To fix firmly or securely: "Today managed care plans are entrenched in the economy, enrolling 61 percent of the population” ( Peter T. Kilborn). (verb-transitive)
• To dig or occupy a trench. (verb-intransitive)
• To encroach, infringe, or trespass. (verb-intransitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Even worse, it often does not manifest until the virus has had time to "entrench" itself in the body, making anti-viral drugs somewhat less effective."
• "This, officials say repeatedly, would only "entrench" the division between Gaza and the West Bank and as such leave the former for Egypt to worry about on its eastern borders."
• "The party wants to change the rules to "entrench" the seats, meaning 75 per cent of MPs would have to agree if they were to be abolished."