“Xero” or “Zero”

xero

No dictionary entry for this spelling — see the usage examples below for how it shows up in writing.

zero z·IH·r·ow

• nouna mathematical element that when added to another number yields the same number.
• nounthe point on a scale from which positive or negative numerical quantities can be measured.
• nounthe sight setting that will cause a projectile to hit the center of the target with no wind blowing.
• verbadjust (an instrument or device) to zero value.
• verbadjust (as by firing under test conditions) the zero of (a gun).
• adjectiveindicating the absence of any or all units under consideration.
• adjectivehaving no measurable or otherwise determinable value.
• adjectiveindicating an initial point or origin.
• adjectiveof or relating to the null set (a set with no members).