What is the meaning of zero?

noun

• A quantity of no importance.
  • usage: "it looked like nothing I had ever seen before"; "reduced to nil all the work we had done"; "we racked up a pathetic goose egg"; "it was all for naught"; "I didn't hear zilch about it"
  • synonyms: nothing, nil, nix, nada, null, aught, cipher, cypher, goose egg, naught, zilch, zip, zippo
• A mathematical element that when added to another number yields the same number.
  • synonyms: 0, nought, cipher, cypher
• The point on a scale from which positive or negative numerical quantities can be measured.
  • synonyms: zero point
• The sight setting that will cause a projectile to hit the center of the target with no wind blowing.

verb

• Adjust (an instrument or device) to zero value.
• Adjust (as by firing under test conditions) the zero of (a gun. )
  • usage: "He zeroed in his rifle at 200 yards"
  • synonyms: zero in

adjective

• Indicating the absence of any or all units under consideration.
  • usage: "a zero score"
  • synonyms: 0
• Having no measurable or otherwise determinable value.
  • usage: "the goal is zero population growth"
• Indicating an initial point or origin.
• Of or relating to the null set (a set with no members. ).