co.
co. — abbreviation
1. short way of writing 'company' in the name of a business, usually placed after a
short way of writing 'company' in the name of a business, usually placed after a personal or family name and an ampersand
The sign above the shop read Tunde & Co. Tailors in gold paint.
appears after personal name + & in business names
Hari worked as a junior accountant at Patel & Co. for nine years.
The lawyer recommended hiring Andrés & Co. to handle the contract review.
Old delivery vans still bear the painted logo of Carter & Co. Bakers.
文法句型
written after a business name
Smith & Co.
用法筆記
Only used inside a registered business name; never replaces the word 'company' in running prose. Always followed by a period in American writing; British writing sometimes drops it.
常見錯誤
2. short way of writing 'county' before the name of a place, used mostly in Irish a
short way of writing 'county' before the name of a place, used mostly in Irish and British postal addresses to mark which county the town belongs to
Élise mailed the parcel to her cousin in Killarney, Co. Kerry, last Friday.
appears before an Irish county name in addresses
Minho rented a small farmhouse in Co. Galway for the summer holiday.
Many old maps of Ireland still label each region with the prefix Co.
The wedding invitation listed the venue as a small chapel in Co. Down.
- Cty.
alternative American abbreviation, common on US road signs and county-level documents
文法句型
written before a county name
Co. Cork
用法筆記
Most common in Irish addresses (Co. Cork, Co. Kerry, Co. Down) and on UK historical maps. Distinguish from sense 1 (company) by position — county 'Co.' precedes a place name; company 'Co.' follows a personal name with '&'.
常見錯誤
3. short way of writing 'Commanding Officer', the person who is in charge of a grou
short way of writing 'Commanding Officer', the person who is in charge of a group of soldiers, sailors, or air crew and gives them their orders
Tariq saluted the CO before stepping into the briefing tent at dawn.
everyday in-service usage: salute / report to the CO
Every platoon leader must report any injuries to the CO within two hours.
Caleb signed the leave request and slid it under the CO's office door.
After the drill, the CO praised the recruits for their teamwork and quick thinking.
- XO
Executive Officer — second-in-command, who reports to the CO
文法句型
used in military communication and documents
the CO of [unit]
用法筆記
Usually written without periods (CO) in modern military style, though older documents and dictionaries still list it as 'co.' Always takes 'the' before it when referring to a specific officer.
常見錯誤
4. two-letter symbol for the US state of Colorado, written after a city name on env
two-letter symbol for the US state of Colorado, written after a city name on envelopes and forms so the postal service knows where to deliver
Hannah addressed the birthday card to her grandmother in Boulder, CO.
standard US postal format: city, CO + ZIP code
The shipping label clearly showed Denver, CO 80202 as the delivery point.
Apinya filled in her new home address as 145 Pine Street, Aspen, CO.
Tax forms require residents to list their state simply as CO, not Colorado.
- Colo.
older traditional abbreviation for Colorado, still seen in books published before the 1960s
文法句型
written after a city name in US postal addresses
Denver, CO 80202
用法筆記
Always written in capital letters as 'CO' (no period) in modern US postal addresses, following the US Postal Service two-letter code system. The period form 'Co.' for Colorado is now rare and appears mostly in older atlases.
常見錯誤
5. short way of writing 'care of', used on letters and parcels to show that a piece
short way of writing 'care of', used on letters and parcels to show that a piece of mail should reach the named person through a different person or address
Sari posted the letter to her brother c/o Mrs. Park at the language school.
commonly written as 'c/o' on the envelope line below the addressee
Please send the documents to me c/o the Tokyo office until further notice.
Tamar's contract should be delivered c/o the legal department on the third floor.
The author asked fan mail to be sent c/o his publisher rather than home.
文法句型
written between two addressees on mail
Name, c/o Other Name
用法筆記
Almost always written as 'c/o' rather than 'co.' on real envelopes. Always names a person or organization after it that will pass the mail on to the real recipient. Distinguish from sense 1 — 'c/o' includes a slash and stands BETWEEN two named parties.
常見錯誤
6. short way of writing 'conscientious objector', a person who refuses to serve in
short way of writing 'conscientious objector', a person who refuses to serve in the army because their religious or moral beliefs are against killing or fighting in war
Eric's grandfather was registered as a CO during the Second World War.
common pattern: registered / classified / known as a CO
The museum displayed letters written by COs who refused to carry weapons in 1942.
Many COs spent the war years working in hospitals or farms instead of fighting.
Quaker families often produced more COs than other religious groups in that era.
- pacifist
broader term — opposes all war on principle; a CO is the formal legal status for refusing military service
- draft resister
American term used during the Vietnam War — refuses to register for the draft, often without claiming religious grounds
- enlistee
person who voluntarily joins the military, opposite stance to a CO
文法句型
used in historical and military records
registered as a CO
用法筆記
Mostly appears in historical writing about the World Wars or in modern conscription debates. The full phrase 'conscientious objector' is preferred in academic and journalistic prose; 'CO' is reserved for archive records and military paperwork.