What is the word for moving your lips without making a sound?

Is there an English word to describe the act of moving one's lips as though speaking but without making a sound? One would do this with the expectation that the person he is attempting to communicate with will read his lips.

As an example, if I walk into my boss's office while he is on the phone and he tells me to "wait a sec..." while wrapping up his phone conversation but without the person on the other end of the phone hearing.

Is there a single word for that?

Mouth. For example, you could write, "She mouthed an 'I love you' to him from across the room".

While most people (myself included) would probably say your boss mouthed something at you, you can also use subvocalize:

tr. & intr.v. sub·vo·cal·ized, sub·vo·cal·iz·ing, sub·vo·cal·iz·es

To articulate or engage in articulation by moving the lips or other speech organs without making audible sounds, as in reading to oneself.

You don't really subvocalize to someone (though you might do so to a computer in the near future) but it does mean moving your lips as if in speech with no sound coming out.