Definition of Zero

Noun: zero (zeros,zeroes) zeer-ow

A mathematical element that when added to another number yields the same number
- 0, nought [Brit], cipher, cypher, naught [N. Amer]
No amount at all; something of no value or importance
- nothing, nil, nix, nada [N. Amer], null, aught [archaic], cipher, cypher, goose egg [N. Amer], naught [N. Amer], zilch, zip, zippo [N. Amer], nought [Brit]
The point on a scale from which positive or negative numerical quantities can be measured
- zero point
The sight setting that will cause a projectile to hit the centre of the target with no wind blowing

Adjective: zero zeer-ow

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

Verb: zero zeer-ow

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