To remove or clear a block or obstruction from.
In whist, to throw away a high card so as not to interrupt one's partner's long suit.
To free or make available.
To enable communication again, via telephone, instant messaging, etc., with (somebody previously blocked).
The removal of a block or blockage.
To unfasten.
To reverse the effects of an action.
To impoverish or ruin, as in reputation; to cause the downfall of.
An operation that reverses a previous action.