Prefix CO examples (24 Common Words and Free PDF)

I’m always searching for new prefixes to teach my students (and blog readers) to help them increase their English vocabulary quickly. Learn the prefix co- with definitions, natural example sentences, and a helpful PDF download. I put together this post for people just like you. 

  • co-author noun
  • co-author verb
  • co-authorship noun
  • co-branding noun
  • co-driver noun
  • co-education noun
  • co-occur verb
  • co-op noun
  • co-opt verb
  • co-parent noun
  • co-parent verb
  • co-pilot noun
  • co-production
  • co-sign verb
  • co-star noun
  • co-star verb
  • co-worker noun
  • coalition noun
  • coincidence noun
  • cooperate verb
  • cooperation noun
  • cooperative adjective
  • coordinate verb

Master these twenty-three words today and start using them in your own English conversations. 

The Prefix CO- Meaning 

co- prefix (used in adjectives, adverbs, nouns, and verbs)

together with

  • co-produced
  • cooperatively
  • co-author

The prefix co- Oxfordlearnersdictionaries.com

Prefix Origin
from Latin – where it has the meaning “joint, jointly, together.” SOURCE

This is ALMOST a true list of words that add CO to another word. All the words on my list are proper root words whose meaning becomes – together with the root word after adding the prefix CO. *With some exceptions* 

Co-op – This is short for cooperation. 
Co-opt – This comes from Latin word cooptare which is: co- ‘together’ + optare ‘choose’.

Verbs like coincide and coordinate are not true prefix words even though they use the prefix co- to mean together. The roots incide and ordinate are not words we use in English by themselves. (The base of both of these words comes from Latin.)

Many of the non-hyphenated prefix co- words are not true prefixes. (Of course, we can recognize the root words operate, operation, and operative as common English words.)

  • I need everyone to cooperate on this.
  • I wish everyone was more cooperative.

The Prefix CO- Examples

co-author noun – a person who writes a book or an article with somebody else

“I’m very happy about the success of my book, but half of the credit goes to my co-author Robin.” 
co-author verb – to write a book or an article with somebody else

“Robin is a young writer, but he’s already co-authored three books that made it onto the Best-Seller list.” 
co-authorship noun – the fact of writing a book or an article with somebody else

Co-authorship is a fine place to start but eventually, you want to start writing your own books.” 

Learn more about the suffix ship- at my blog post here: The Suffix -ship (Over 30 Examples + Real Sentences)

Bruce and Connie have co-authored 9 books.
co-branding noun – a marketing strategy in which two companies work together to sell their products or services, using both company names

“The athletics wear company is co-branding with a soda manufacturer. They will make baseball clothes and gear with the athletic wear company logo and the drink company product name.”
co-driver noun – a person who shares the job of driving a vehicle with another

“My brother wanted to take his car to University. It was a long drive so I went with him to his school as a co-driver. This way he could take a break every few hours and we could still keep moving. I came home by train the next day.” 
co-education noun– the practice of teaching girls and boys together in a school

“Single-sex education was more common up to the 19th century, co-education has since become standard in many cultures.” SOURCE

This is often abbreviated as co-ed
“In my High School gym class some of the activities were coed, boys and girls participated together.” 

We played coed soccer in elementary school.

In older North American English the word coed was used as a noun to mean: a female student at a co-educational school or college.

co-occur verb – to occur together or at the same time

“Some symptoms of the flu often co-occur. People often feel body aches and tiredness at the same time.”
*Note – This word is not so common in conversation. It’s much more common to just say “happen at the same time.
co-op noun – cooperative shop, society or business (A cooperative shop is a shop that is owned and run by the people involved, with the profits shared by them.)

“I like to get groceries from the local co-op. It’s much cheaper than regular grocery stores.”
co-opt verb – to change somebody/something to a different role from the usual or original one; to take somebody’s idea and use it for your own purposes

“I want to talk to the boss in private. If I share an idea at the meeting in front of everyone, I’m sure Mike or Larry will try to co-opt it.” 
Ideas are stolen all the time. Be sure to protect your ideas against bad people.
co-parent noun – a person who shares the duties of bringing up a child

“Shelly and Brandon remained friends after the divorce and thought it was best to work together as co-parents to bring up their 4-year-old daughter.” 
co-parent verb –  to share the duties of bringing up a child, especially when a couple are separated or not married

“Shelly and Brandon still live in the same city making it easier to co-parent their daughter.”
co-pilot noun – a second pilot who helps the main pilot in an aircraft

“In the airport lounge, I had a long conversation which one of the airline’s co-pilots. He was an interesting guy.” 
co-production noun – a joint venture between two or more different production companies for the purpose of film production, television production, video game development, and so on.

“The movie is a co-production between a big studio and the main actor’s own production company.”
co-sign verb – to sign a legal document for somebody else, in addition to their own signature, in order to promise that an agreement will be kept

“My dad had to co-sign the payment agreement because I was only 17.”
co-star noun – one of two or more famous actors who appear together in a film or play

“It was the first time a reporter had called the young actor a co-star during an interview. It made him smile.”
co-star verb – to appear as one of the main actors with somebody in a play or film

“Having the opportunity to co-star in a movie with Tom Cruise was a huge event in the young actor’s life.”
co-worker noun – a person that somebody works with, doing the same kind of job

“Today was one of my co-workers’ birthday so we all got to eat cake during our lunch break. I like cake.”
I work in a big office so we have cake almost every week!

Non-hyphenated Words with the Suffix CO-

coalition noun – 1) a government formed by two or more political parties working together

  • Two political parties have formed a coalition government.

2) a group formed by people from several different groups, especially political ones, agreeing to work together for a particular purpose

  • The group is a global coalition trying to stop the trade of conflict diamonds out of Africa. 

coexist verb – to exist together in the same place or at the same time, especially in a peaceful way

  • Cattle farmers and wolves are struggling to coexist in recent years. The wolves hunting grounds are being destroyed so they have started attacking calves on local farms for food.

coincidence noun – the fact of two things happening at the same time by chance, in a surprising way

  • I walked around the office trying to find Martin, and then he took the same elevator as me. That was a lucky coincidence

The noun coincidence comes from the verb coincide which means – to happen at the same time. 

cooperate verb – to work together with somebody else in order to achieve something

  • This is an important project so I need everyone to cooperate on this.

cooperation noun – the fact of doing something together or of working together towards a shared aim

  • Cooperation will be the key to our success. Make sure that we are all working together and supporting each other.

“If you want to go fast, go alone. If you want to go far, go together.”

cooperative adjective – helpful by doing what you are asked to do

  • I wish everyone was more cooperative. There is too much competition at the office.

coordinate verb – 1) to organize the different parts of an activity and the people involved in it so that it works well

  • What are my responsibilities is to coordinate the efforts of each group member. 

2) to make the different parts of your body work well together

  • The injury affected the part of his brain that coordinates body movement making it difficult for him to walk. 

3) if you coordinate clothes, furniture, etc. or if they coordinate, they look nice together

  • It’s important to coordinate your shoe and belt colors when you dress formally.
Your belt should always match your shoes.

Can you think of any other common words with co- that I didn’t include? Tell me in the comments.

Prefix CO- PDF E-guide

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