Co

¹ American  

Symbol, Chemistry.

1. cobalt.

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CO ² American  

abbreviation

1. Colorado (approved especially for use with zip code).

2. commanding officer.

3. conscientious objector.

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Co. ³ American  

Or co.

abbreviation

1. Company.

2. County.

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c/o ⁴ American  

1. care of.

2. Bookkeeping. carried over.

3. cash order.

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C/o ⁵ American  

1. care of.

2. Bookkeeping. carried over.

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C/O ⁶ American  

1. cash order.

2. certificate of origin.

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co- ⁷ American  

1. variant of com- before a vowel, h, and gn: coadjutor; cohabit; cognate . The prefix co- now productively forms new words from bases beginning with any sound (co-conspirator; co-manage; coseismic ), sometimes with the derived sense “auxiliary, subsidiary” (coenzyme; copilot ), and, in mathematics and astronomy, with the sense “complement” (codeclination ).

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c.o. ⁸ American  

abbreviation

1. care of.

2. carried over.

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C.O. ⁹ American  

abbreviation

1. cash order.

2. Commanding Officer.

3. conscientious objector.

4. correction officer.

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CO ¹ British  

abbreviation

1. Commanding Officer

2. Commonwealth Office

3. conscientious objector

4. Colorado

5. Colombia (international car registration)

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co- ² British  

prefix

1. together; joint or jointly; mutual or mutually

   coproduction

2. indicating partnership or equality

   cofounder

   copilot

3. to the same or a similar degree

   coextend

4. (in mathematics and astronomy) of the complement of an angle

   cosecant

   codeclination

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Co ³ British  

abbreviation

1. (esp in names of business organizations) Company

2. informal and the rest of them

   Harold and co

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c/o ⁴ British  

abbreviation

1. care of

2. accounting carried over

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co ⁵ British  

abbreviation

1. a commercial company (used with a country domain name)

2. Colombia

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Co ⁶ British  

symbol

1. cobalt

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Co ⁷ British  

abbreviation

1. County

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Etymology

Origin of co-

from Latin, reduced form of _com-

Example Sentences

She said that another catalyst for the company is the fact that Taiwan Semiconductor Manufacturing Co.

From MarketWatch • Apr. 1, 2026

In consumer staples there were four names: Kimberly-Clark, yielding 5.3%; McCormick & Co.

From Barron's • Apr. 1, 2026

Eugene Drennan is a former President of the Irish Road Haulage Association and runs a haulage company based in Co Clare.

From BBC • Mar. 25, 2026

The microdrama category is worth an estimated $3 billion in annual subscription fees and ad sales outside the Chinese market, according to media research firm Owl & Co.

From The Wall Street Journal • Mar. 18, 2026

The octave below contra can be labelled CCC or Co; higher octaves can be labelled with higher numbers or more lines.

From "Understanding Basic Music Theory" by Catherine Schmidt-Jones and Russel Jones