To block or fill (a passage) with obstacles or an obstacle. See synonyms at block.
To get in the way of so as to hide from sight.
To impede, retard, or interfere with; hinder.
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.