unblock has 3 distinct synonyms spread across 1 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is block.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
clear or remove an obstruction from
“the procedure unblocked his arteries”
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
Synonyms, antonyms and the broader and narrower relations for unblock come from Princeton University’s WordNet. Full sources and licences.
make (assets) available
“release the holdings in the dictator's bank account”