Definition of "zero" [ze•ro]

• The numerical symbol 0; a cipher. (noun)
• Mathematics The identity element for addition. (noun)
• Mathematics A cardinal number indicating the absence of any or all units under consideration. (noun)
• Mathematics An ordinal number indicating an initial point or origin. (noun)
• Mathematics An argument at which the value of a function vanishes. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The term "zero tolerance" came into popular usage during the Reagan presidency when Congress passed the Drug-Free Schools and Communities Act."
• "The potential of electric vehicles and fuel cell vehicles to dramatically cut emissions from cars is tremendous, though the term "zero emissions motoring" needs to be treated with caution."
• "Over the past two months in particular, Turkey's leaders have been adjusting a foreign policy that went under the rubric "zero problems with neighbors" to changes forced by the Arab Spring, analysts say."