Colleague (noun)

1. A person with whom one works in a profession or business.
2. A person working in the same organization or profession as oneself.
3. A person working in the same organization or profession as you.

Origin:

Early 17th century: from french collègue, or via latin from collega "partner in office", from col- "together" + legare "to send".

Examples:

1. She is my colleague at work.
2. He is my colleague in the department.
3. They are my colleagues in the field.
4. We are colleagues at the company.
5. I am a colleague of hers.