Definition of "dig in"

dig in

verb
third-person singular simple present digs in, present participle digging in, simple past and past participle dug in
1. (colloquial) To begin eating.
2. (colloquial) To engage in a burst of hard work.
  Quotations
  Mancini's men were far from their best but dug in to earn a 10th win in 11 league games and an eighth successive victory in all competitions to maintain their five-point lead at the top of the table.
  2011 November 5, Phil Dawkes, “QPR 2 - 3 Man City”, in BBC Sport‎
3. (military, also figurative in sports) To dig trenches to resist an enemy attack.
  Quotations
  If Russia choses to dig in, then the military balance – which typically favours the defender on a 3-1 ratio – is reversed.
  2022 April 4, Dan Sabbagh, “Routing of Russian forces from Kyiv area will be hard to repeat in eastern Ukraine”, in The Guardian‎
4. (idiomatic) To adopt a resolute state of mind.
5. To cover over by digging.