unblock -- (clear or remove an obstruction from; "the procedure unblocked his arteries")
unblock -- (play the cards of (a suit) so that the last trick on which a hand can follow suit will be taken by a higher card in the hand of a partner who has the remaining cards of a combined holding)
unblock, unfreeze, free, release -- (make (assets) available; "release the holdings in the dictator's bank account")