coworker
n.someone you work with, usually at the same level as you in a company.
n.a person with whom one works, typically in a professional or office environment. Often implies a peer relationship rather than a hierarchical one.
“I am going to lunch with a coworker today.”
“After the meeting, a coworker helped me finish the presentation so we could submit it before the deadline.”
“Maintaining professional boundaries with a coworker can be challenging when the collaborative nature of the project encourages a more personal friendship outside of office hours.”
Commonly used in American English; 'colleague' is often preferred in British English or more formal contexts.
Learners sometimes combine 'workmate' and 'coworker', but these are synonyms and should be used separately.
From co- + worker.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.