noun

• (uncountable) The act of excavating, or of making hollow, by cutting, scooping, or digging out a part of a solid mass.
  "Near-synonyms: hollowing out, hollowing"
• (uncountable) The act of excavating, or of making hollow, by cutting, scooping, or digging out a part of a solid mass.
• (countable) A cavity formed by cutting, digging, or scooping.
  "Prof. Dainelli made a personal study of the lakes of the Upper Indus lying between its confluence with the Gilgit on the west and the plains of Kashmir on the east. From this district he cites fifty lakes and groups of lakes. Many of these are moraine-dammed, but some of the larger ones, as the Satpor Tso, the Tso Moriri, the Chiun Tso, and the group of lakes associated with the Pángong Tso, he considers to have originated by glacial excavation."
• (countable) An uncovered cutting in the earth, in distinction from a covered cutting or tunnel.