Dig \Dig\, v. i.

1. To work hard or drudge; specif. (U. S.): To study ploddingly and laboriously. [Colloq.]

Peter dug at his books all the harder. --Paul L. Ford.

2. (Mach.) Of a tool: To cut deeply into the work because ill set, held at a wrong angle, or the like, as when a lathe tool is set too low and so sprung into the work.

To dig out, to depart; to leave, esp. hastily; decamp. [Slang, U. S.]

Source: Webster's Revised Unabridged Dictionary (1913)