Discussion Forum—A Way with Words, a fun radio show and podcast about language

I would almost call this an idiom except that the object changes with every situation.   In this situation "professional" is used as the highest kind of relationship, so "more than" would not fit.   In other situations other objects are plugged in and used as the utmost.   For example, "They had a less than private conversation," or "He was less than eager to go on the trip."   You will often hear the term, "less than ideal," because ideal is always the highest expectation. But never "more than" because you can't get more than the highest.

Somebody tell me what this is called.   Is it really an idiom or something else?

Here is an edit about 10 hours after the original post.

My mind finally kicked in and I realized that the more common expression is "less than perfect."   It may be that every other "less than" expression is derived from this. But you'll never see anything that is "more than perfect" unless someone is trying to exaggerate.

I agree with Dilettante. It would be "professional" to keep a cordial distance between two coworkers. A romantic relationship in the workplace is still frowned upon in most companies. Of course, this isn't true on TV.

I think, Robert, you're thinking of "more than" in the sense that it would be "more than casual" or "more than friends" in the sense that a romantic rapport is deemed desirable. In the same sense, casual partners are often called "friends with benefits" which kind of implies that a platonic friendship doesn't have any benefits.  

I suppose in your show, the partners in the relationship see their coupling as a plus, but those around them may deem it a minus in that it complicates things in the workplace.