ze·ro (zîrō, zērō)
n. pl. ze·ros or ze·roes
1. The numerical symbol 0; a cipher.
a. The identity element for addition.
b. A cardinal number indicating the absence of any or all units under consideration.
c. An ordinal number indicating an initial point or origin.
d. An argument at which the value of a function vanishes.
3. The temperature indicated by the numeral 0 on a thermometer.
4. A sight setting that enables a firearm to shoot on target.
5. Informal One having no influence or importance; a nonentity: a manager who was a total zero.
6. The lowest point: His prospects were approaching zero.
7. Informal Nothing; nil: Today I accomplished zero.
1. Of, relating to, or being zero.
a. Having no measurable or otherwise determinable value.
b. Informal Not any; no: "The town has ... practically no opportunities for amusement, zero culture" (Robert M. Adams).
a. Designating a ceiling not more than 16 meters (52 feet) high.
b. Limited in horizontal visibility to no more than 55 meters (180 feet).
4. Linguistics Of or relating to a morpheme that is expected by an established, regular paradigm but has no spoken or written form. Moose has a zero plural; that is, its plural is moose.
tr.v. ze·roed, ze·ro·ing, ze·roesPhrasal Verbs:
To adjust (an instrument or a device) to zero value.
a. To aim or concentrate firepower on an exact target location.
b. To adjust the aim or sight of by repeated firings.
2. To converge intently; close in: The children zeroed in on the display of toys in the store window.
1. To reduce to zero.
2. To eliminate (a budget or budget item) by cutting off funding.
[Italian, from alteration of Medieval Latin zephirum, from Arabic ṣifr, nothing, cipher; see CIPHER.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.