Definitionen
1.VerbTo remove or clear a block or obstruction from."We need a plumber to unblock the sink."
2.VerbTo free or make available.
3.VerbIn whist, to throw away a high card so as not to interrupt one's partner's long suit.
4.VerbTo enable communication again, via telephone, instant messaging, etc., with (somebody previously blocked).
5.NounThe removal of a block or blockage.