Definitions of pit:

• noun:   a surface excavation for extracting stone or slate

  Example: "A British term for `quarry' is `stone pit'"

• noun:   a trap in the form of a concealed hole
• noun:   a sizeable hole (usually in the ground)

  Example: "They dug a pit to bury the body"

• noun:   a concavity in a surface (especially an anatomical depression)
• noun:   a workplace consisting of a coal mine plus all the buildings and equipment connected with it
• noun:   lowered area in front of a stage where an orchestra accompanies the performers
• noun:   the hard inner (usually woody) layer of the pericarp of some fruits (as peaches or plums or cherries or olives) that contains the seed
• verb:   set into opposition or rivalry

  Example: "Pit a chess player against the Russian champion"

• verb:   remove the pits from

  Example: "Pit plums and cherries"

• verb:   mark with a scar