WordNet records no synonym and no antonym for shutter. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
a mechanical device on a camera that opens and closes to control the time of a photographic exposure
Synonyms, antonyms and the broader and narrower relations for shutter come from Princeton University’s WordNet. Full sources and licences.
close with shutters
“We shuttered the window to keep the house cool”