officemate
/ˈɒfɪsiˌmeɪt/Definitions
1. noun
a person who works in the same office as another person, especially a colleague or fellow employee
“She was friendly with her officemate from the marketing department.”
2. noun
a person who shares the same office space, often used to refer to a roommate or someone living in the same dwelling
“They had an argument with their officemate about the rent.”