WordNet records no synonym and no antonym for scaffold. 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 platform from which criminals are executed (hanged or beheaded)
a temporary arrangement erected around a building for convenience of workers
Synonyms, antonyms and the broader and narrower relations for scaffold come from Princeton University’s WordNet. Full sources and licences.
provide with a scaffold for support
“scaffold the building before painting it”