close up has 18 distinct synonyms spread across 5 of its 5 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 open up.
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.
cease to operate or cause to cease operating
“The owners decided to move and to close the factory”
Synonyms, antonyms and the broader and narrower relations for close up come from Princeton University’s WordNet. Full sources and licences.