say it: ZIR-oh
zero is a noun, adjective and verb meaning "a quantity of no importance". It carries 10 recorded senses.
the point on a scale from which positive or negative numerical quantities can be measured
the sight setting that will cause a projectile to hit the center of the target with no wind blowing
indicating an initial point or origin
of or relating to the null set (a set with no members)
adjust (an instrument or device) to zero value
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for zero come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.