To limit or restrict.
To narrow, especially by application of pressure.
To coil around (prey) in order to asphyxiate it.
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.