DIG (4)

Dig, v. i. 1. 1. To work hard or drudge; specif. (U. S.): To study ploddingly and laboriously.
Peter dug at his books all the harder. Paul L. Ford. 2. 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.