Word Origin & History
early 14c. (diggen), of uncertain origin, probably related to dike and ditch, either via O.Fr. diguer (ult. from a Gmc. source), or directly from an unrecorded O.E. word. Native words were deolfan, grafan (medial -f- pronounced as "v" in O.E.). Meaning "thrust or poke" (as with an elbow) is from 1819;
figurative sense of this is from 1840. Slang sense of "understand" first recorded 1934 in Black English, probably based on the notion of "excavate." A slightly varied sense of "appreciate" emerged 1939. Noun meaning "archaeological expedition" is from 1896. Related: Digging.