adj.
1.indicating the absence of any or all units under consideration
2.indicating an initial point or origin
3.of or relating to the null set (a set with no members)
4.having no measurable or otherwise determinable value zero n.
1.a quantity of no importance
2.a mathematical element that when added to another number yields the same number
3.the quantity that registers a reading of zero on a scale zero v.
1.adjust (an instrument or device) to zero value
2.adjust (as by firing under test conditions) the zero of (a gun)