zero

Sense 1 noun

a quantity of no importance

it looked like nothing I had ever seen before

Sense 2 verb

adjust (an instrument or device) to zero value

Sense 3 adjective

indicating the absence of any or all units under consideration

a zero score

Sense 4 noun

a mathematical element that when added to another number yields the same number

Sense 5 verb

adjust (as by firing under test conditions) the zero of (a gun)

He zeroed in his rifle at 200 yards

Sense 6 noun

the point on a scale from which positive or negative numerical quantities can be measured

Sense 7 adjective

indicating an initial point or origin

Sense 8 noun

the sight setting that will cause a projectile to hit the center of the target with no wind blowing

Sense 9 adjective

of or relating to the null set (a set with no members)