co
word
Definition
'Co' is often used as a prefix meaning 'together with' or 'joint', as in 'co-worker' or 'co-founder'. It can also be an informal abbreviation for 'companion' or someone you do something with.
Usage & Nuances
'Co-' is mostly used as a prefix in formal and informal English, especially to indicate shared roles, as in 'co-author' or 'co-host'. As a standalone abbreviation ('my co'), it is informal and less common, usually used in quick notes or digital communication. Always hyphenate when forming compound nouns, e.g., 'co-founder'.
Example Sentences
We are co-workers in the same company.
basic
She is a co-author of the book.
basic
We need a co-signer for the contract.
basic
My co and I finished the project late last night.
natural
I texted my co about the meeting time.
natural
Let's co-host the event—it'll be more fun together.
natural