Verb

(head)

(undermine)

Verb

(undermin)

To dig underneath (something), to make a passage or for destructive or military purposes; to sap.

* 2009 , (Diarmaid MacCulloch), A History of Christianity , Penguin 2010, p. 312:

Martin, for instance, had on one occasion undermined a tree sacred to old gods, then stood in the path of its fall, but forced it to fall elsewhere by making the sign of the Cross.

(figuratively) To weaken or work against; to hinder, sabotage.

* {{quote-news, year=2012, date=April 19, author=Josh Halliday, work=the Guardian

, title= Free speech haven or lawless cesspool – can the internet be civilised? , passage=The growing use of social media to spread anger and dissent in the Arab world has been hailed by western governments as one of the chief justifications for a completely unfettered internet. The US is reportedly funding the secret rollout of technology in Iran in an effort to undermine internet censors in the country.}}

Verb

(head)

(underpin)

Verb

(underpinn)

To support from below with props or masonry.

You should underpin the mine roof to prevent further collapse.

(figuratively) To give support to; to corroborate.

Public confidence in politicians must underpin our democracy.