Dig In

1. Excavate trenches and hold one's position. 2. Adopt a firm, obstinate stance. 3. Begin to work intensively. 4. Begin to eat heartily.

Examples:

• Arthur refused to argue the point and simply dug in.
• If we all dig in it'll be done before dark.
• When the bell rang, the kids all dug into their lunches.

Origin: Colloquial; late 1800s for most senses.