invisible:

The condition of being unable to be seen; what you become when someone you know is around you but does not want to be associated with you, usually because he or she is kissing the ass of someone more important nearby; also, a mutual invisibility that occurs when two parties make an unspoken agreement to not see each other, such as when you still run into someone you briefly dealt with three years before and neither of you can muster the energy to say hi to each other anymore.

Courtesy of the Dictionary of Corporate Bullshit page-a-day calendar…