Definition
A man or woman in the workplace with whom one shares a special relationship similar to marriage, with confidences, loyalties, shared jokes and experiences, and an unusual degree of honesty or openness.
How People Actually Use It
A significant other you work with, whom you connect, share, and spend time with exclusively and intimately in the workplace. Both parties are mere aquaintances outside of the workplace and are completely unknown to each others true and respective domestic spouses.
""Rumor has it that those two are dating." "That's completely untrue. Heidi is just Allan's work spouse. That relationship ceases to exist after their 8 hour shift.""
Source: Urban Dictionary