unblock (Verb) — Clear or remove an obstruction from. ex. "the procedure unblocked his arteries"
unblock (Verb) — (card game) 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 (Verb) — Make (assets) available. ex. "unblock the holdings in the dictator's bank account"