The Meaning of C/O: What It Is and How To Use It

Do you know the definition of C/O? This article will provide you with all of the information you need on the abbreviation C/O, including its definition, usage, examples, and more!

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According to Cards Direct, ℅ stands for care of. This is a way of addressing someone that indicates it is supposed to be delivered to an addressee in a place where they do not normally receive mail or correspondence. This term lets the post office know that the recipient of the mail is not the normal recipient at that address. For example, if a friend was traveling and staying at a hotel, you could send them a package or letter to the notel, addressed to “Friend’s Name ℅ Hotel Name.”

In order to use this, you would write the recipient’s name on the first line of the letter like normal. Then on the second line you would write “℅” followed by the person at the address you are using. This can be used in business, for people who are traveling on vacation, or for an event invitation. This is similar to using an “attention” or “attn” on a letter, but is slightly different. “Attention” is used when you are sending something to a business or location with multiple people present. For example, if you were addressing a letter to the employee of a business, you could address it, “Business Name Attn: John Doe.” You will most commonly see abbreviations like this on envelopes that are not going to a person’s home address or typical street address. The USPS is aware of these terms that can be used by a sender for shipping purposes. This is considered necessary information just like a return address on a piece of mail. 

Co is also a prefix used on many different words that means “auxiliary or helping.” This can be used on words such as the following list from Word Reference and Word Example.

  • covariance
  •  cove
  •  contractor
  •  contestable
  •  cornmill
  •  corroboration
  •  conurbation
  •  comrade
  •  comically
  •  convection
  •  condescension
  •  coca
  •  continuously
  •  cointreau
  •  countdown
  •  conspicuous
  •  collation
  •  concertina
  •  continental
  •  colonnade
  •  conductor
  •  coq
  •  constrain
  •  coke
  •  correction
  •  contrastive
  •  collaboration
  •  corfe
  •  coy
  •  conversant
  •  counter-attack
  •  coax
  •  conundrum
  •  coarseness
  •  contemporaneous
  •  collector
  •  counterclaim
  •  condor
  •  confide
  •  court
  •  copy
  •  coalite
  •  comp
  •  contralto
  •  couplet
  •  cobb
  •  convocation
  •  conscription
  •  considerable
  •  converge
  •  confidential
  •  cognac
  •  costa
  •  courtesan
  •  continence
  •  cox
  •  conscientiously
  •  cogently
  •  contention
  •  countryman
  •  compulsion
  •  continuum
  •  contemporary
  •  conceit
  •  connotation
  •  covert
  •  computerisation
  •  contralateral
  •  corgi
  •  common-sense
  •  competitiveness
  •  conveyor
  •  comprehend
  •  collarbone
  •  compunction
  •  cognition
  •  conscript
  •  conformity
  •  commendation
  •  co-operatively
  •  coward
  •  correct
  •  condense
  •  collegiate
  •  colander
  •  comm
  •  counterfeit
  •  congruence
  •  cockney
  •  coterie
  •  county
  •  courtesy
  •  corrosive
  •  compile
  •  connector
  •  conformational
  •  covertly
  •  conduction
  •  cohen
  •  comely
  •  cohabitation
  •  conception
  •  communion
  •  copier
  •  complementarity
  •  coverage
  •  collins
  •  convention
  •  councillor
  •  communal
  •  complementary
  •  cole
  •  contamination
  •  consternation
  •  coercive
  •  competence
  •  congratulatory
  •  corinthian
  •  courier
  •  couple
  •  coincidentally
  •  comital
  •  cohesiveness
  •  co-ordination
  •  confessional
  •  cogency
  •  correspondent
  •  consequential
  •  corn
  •  continuance
  •  compatibility
  •  conflagration
  •  combe
  •  corporation
  •  confiscation
  •  contributor
  •  component
  •  cowling
  •  corpus
  •  codon
  •  confidently
  •  commute
  •  conservatism
  •  correlation
  •  co-opt
  •  correspondence
  •  compact
  •  cook
  •  combustion
  •  cosmo
  •  consistency
  •  comber
  •  coincidental
  •  coordinate
  •  constancy
  •  contour
  •  cornerstone
  •  collaborate
  •  cosmic
  •  cottage
  •  constable
  •  collective
  •  corky
  •  conveniently
  •  corps
  •  collar
  •  confuse
  •  compel
  •  cookery
  •  constructional
  •  communally
  •  conn
  •  confidante
  •  consonant
  •  copyright
  •  cornflower
  •  conclusion
  •  cold-blooded
  •  convulsion
  •  corset
  •  commonality
  •  combination
  •  compliant
  •  cone
  •  collect
  •  contentedly
  •  constitutionally
  •  copse
  •  contextually
  •  committee
  •  con
  •  cortina
  •  conqueror
  •  communicate
  •  convict
  •  completely
  •  concretion
  •  consciously
  •  connie
  •  contribute
  •  contestant
  •  covent
  •  compress
  •  compare
  •  coldness
  •  counter
  •  collie
  •  cowper
  •  colouration
  •  contaminate
  •  co-exist
  •  coach
  •  coincident
  •  companionway
  •  contributory
  •  constitute
  •  consort
  •  conciliar
  •  colin
  •  controversy
  •  controversial
  •  compressor
  •  convalescent
  •  commercially
  •  coral
  •  conscientious
  •  confession
  •  cousin
  •  co-defendant
  •  copilot
  •  coenzyme
  •  codeclination
  •  conspirator
  •  coadjutor
  •  counterproductive
  •  congregationalist
  •  corsair
  •  conductance
  •  contractual
  •  commandment
  •  consul
  •  comparative
  •  constellation
  •  compaction
  •  comical
  •  corduroy
  •  coordination
  •  complainant
  •  courgette
  •  complex
  •  communicable
  •  cognisance
  •  contribution
  •  coup
  •  confetti
  •  contractile
  •  content
  •  coalition
  •  concise
  •  collectively
  •  concern
  •  colourful
  •  corporatist
  •  coronation
  •  consecration
  •  compass
  •  copulation
  •  cordless
  •  comb
  •  computational
  •  confirmation
  •  colliery
  •  confiscate
  •  courage
  •  courthouse
  •  containment
  •  colonic
  •  colourless
  •  codex
  •  cosmetic
  •  coil
  •  colt
  •  collusion
  •  conservative
  •  commemoration
  •  co-star
  •  commercial
  •  corpuscular
  •  controller
  •  correspondingly
  •  colony
  •  consent
  •  conditional
  •  comic
  •  collusive
  •  convey
  •  codification

According to The Free Dictionary, the acronym ℅ can stand for much more than just care of. These other definitions are perfectly valid, but they are far less common. Because of this, you should use them sparingly. These are also normally not used with a slash in between. If you do decide to use one of these other definitions for this acronym, make sure that the listener or reader has the proper context so that they are not confused. When in doubt, use the full meaning of ℅.

  •  Congregation of the Oratory, Oratorians (religious order)
  •  Champions Online (game)
  •  Cargo Oil
  •  County
  •  Conscientious Objector
  •  Corporación (Spanish)
  •  Conseiller d’Orientation (French)
  •  Castor Oil
  •  Certifying Officer
  •  Course
  •  Covert Operations (gaming)
  •  Cabinet Office
  •  Charlotte Observer (newspaper)
  •  Conservation Operations
  •  Command
  •  Cobalt
  •  Change Order
  •  Clerical Officer (obsolete, now AO)
  •  Correction Officer
  •  Combinatorics and Optimization (field of pure mathematics)
  •  Cash Out (mortgage refinancing)
  •  Consumer Ombudsman (UK)
  •  Clinical Operations
  •  Central Office (telecommunications/telephony)
  •  Cash Order
  •  Community Organizer (Philippines)
  •  Circle Officer (India)
  •  Controlling
  •  Coastal Chart
  •  Conference
  •  Command Operations
  •  Cornish (linguistics)
  •  Circuit Overseer (Jehovah’s Witnesses)
  •  Ciceronian Oration
  •  Correctional Officer
  •  Cargo Operations
  •  Chinese Orchestra
  •  Consent Order
  •  Captive Office (Nortel)
  •  Collection Officer
  •  Certified Orthotist (ABC)
  •  Command Outpost
  •  crude oil
  •  Company
  •  Connection Oriented
  •  Continental Airlines (airline code)
  •  Cardiac Output
  •  Chief Officer
  •  Comercializadora de Occidente SA (Guatemala)
  •  Clean Out (sewers/drains)
  •  Combat Aptitude Area
  •  Clinical Officer (hospital)
  •  Custodial Officer
  •  Combinatorial Optimization (workshop)
  •  Case Operations
  •  Constraint Oriented
  •  Colton (blood group)
  •  Constant Observation (medical care)
  •  Convert Out
  •  Colombia
  •  Commanding Officer
  •  Combined Operations (gaming)
  •  Contracting Officer
  •  Chief Operator
  •  Core Operation(s)
  •  Complement (mathematics, astronomy)
  •  Comitissa (Latin: Countess, Codices And Manuscripts)
  •  Chosen Overseer
  •  Air Post Official (Scott Catalogue prefix; philately)
  •  Columbia Orchestra (Ellicott City, MD)
  •  Carbon Monoxide
  •  Commitment to Perform (common feature; Capability Maturity Model Integration)
  •  Colchester (postcode, United Kingdom)
  •  Current Operations
  •  Community Outreach
  •  Communications Officer
  •  .CO (Internet country code top-level domain)
  •  Checkout
  •  Certificate of Occupancy
  •  Colorado (US postal abbreviation)
  •  Compliance
  •  Consoleone (Novell GUI)
  •  Captain Obvious
  •  Commissioned Officer
  •  Caucasian Ovtcharka (dog breed)
  •  Chill Out
  •  Command Output
  •  Compliance Officer
  •  Clothes Optional
  •  Compliance Order
  •  Colonial Office (UK)
  •  Cutoff
  •  Call-Out
  •  Combat (game, Natural Selection)
  •  Certificate of Origin
  •  Compañía (Spanish)
  •  Complain Of
  •  Consolidated Obligation
  •  Cellular One
  •  Contracting Official
  •  Conan O’Brien
  •  Como (Lombardia, Italy)
  •  Carbon Monoxide gas (poisonous gas and  product of incomplete combustion of carbon cobalt)

Overall, ℅ stands for care of. This slang term is used on paperwork, an envelope or package to signify that the addressee’s name is not who is normally at said address. 

Sources:

  1. How to Use “Care of” or C/O in an Address | Cards Direct 
  2. CO – What does CO stand for? | The Free Dictionary 
  3. CO | Word Reference 
  4. Words with the prefix “co-” (1,000 results) | Word Example