Co

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).

Other definitions for Co (4 of 9)

c/o

care of.

Bookkeeping. carried over.

cash order.

Other definitions for Co (5 of 9)

c.o.

abbreviation

care of.

carried over.

Other definitions for Co (6 of 9)

Co.

or co.

abbreviation

Company.

County.

Other definitions for Co (7 of 9)

C/o

care of.

Bookkeeping. carried over.

Other definitions for Co (8 of 9)

C/O

cash order.

certificate of origin.

Other definitions for Co (9 of 9)

C.O.

abbreviation

cash order.

Commanding Officer.

conscientious objector.

correction officer.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use Co in a sentence

“C O U R D O R O Y,” he said, saying each letter and then proudly declaring the word.
All Kids Want a Head Start|Eleanor Clift|February 13, 2014|DAILY BEAST
Since it all goes well write me c/o of Bulter address and I will be sure to get them.
The Escape of a Princess Pat|George Pearson
"I c-c-c-o-o-ouldn't help it," sputtered Ding-dong sorrowfully.
The Motor Rangers Through the Sierras|Marvin West
Well, when we moved here a week and a half ago and got settled a delegation from the ranks waited on the C. O.
The Glory of The Coming|Irvin S. Cobb

Would you be kind enough to return the book to me c/o this Institute when you are finished with it?
Starman's Quest|Robert Silverberg
While the Columbia grammar boys would reply, “C-o-l-u-m-b-i-a—Burke!”
Witch Winnie's Mystery, or The Old Oak Cabinet|Elizabeth W. Champney

British Dictionary definitions for Co (1 of 7)

the internet domain name for

a commercial company (used with a country domain name)

Colombia

British Dictionary definitions for Co (2 of 7)

Co¹

the chemical symbol for

cobalt

British Dictionary definitions for Co (3 of 7)

Co²

abbreviation for

County

British Dictionary definitions for Co (4 of 7)

Co³

co

abbreviation for

(esp in names of business organizations) Company

and co (kəʊ) informal and the rest of themHarold and co

British Dictionary definitions for Co (5 of 7)

abbreviation for

Commanding Officer

Commonwealth Office

conscientious objector

Colorado

Colombia (international car registration)

British Dictionary definitions for Co (6 of 7)

co-

prefix

together; joint or jointly; mutual or mutuallycoproduction

indicating partnership or equalitycofounder; copilot

to the same or a similar degreecoextend

(in mathematics and astronomy) of the complement of an anglecosecant; codeclination

Word Origin for co-

from Latin, reduced form of com-

British Dictionary definitions for Co (7 of 7)

c/o

abbreviation for

care of

accounting carried over

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for Co

The symbol for cobalt.