Need a fourth widget for term reference fields.

I’m trying to allow my users to enter term X into vocabulary X, but I do not want users to be able to see existing terms. For example, a user can enter a couple characters and autocomplete produces all terms with those characters. I don’t want users to see those.

I can’t locate any modules that address this. A fourth widget type would be nice just for user input. The same way “username” in new account creation allows the input without rendering existing usernames. And if the input is unique it passes, and if it matches an existing pattern it fails.

I’m using D7.

Is anyone aware of a solution?

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/22/feed